diff --git a/apisix/admin/consumers.lua b/apisix/admin/consumers.lua
index e02789069c64..d78800767c44 100644
--- a/apisix/admin/consumers.lua
+++ b/apisix/admin/consumers.lua
@@ -17,7 +17,7 @@
 local core    = require("apisix.core")
 local plugins = require("apisix.admin.plugins")
 local resource = require("apisix.admin.resource")
-
+local utils = require("apisix.admin.utils")
 
 local function check_conf(username, conf, need_username, schema)
     local ok, err = core.schema.check(schema, conf)
@@ -30,10 +30,17 @@ local function check_conf(username, conf, need_username, schema)
     end
 
     if conf.plugins then
+        -- check_schema encrypts the key in the plugin.
+        -- check duplicate key require the original key.
+        local conf_plugins_copy = core.table.deepcopy(conf.plugins)
         ok, err = plugins.check_schema(conf.plugins, core.schema.TYPE_CONSUMER)
         if not ok then
             return nil, {error_msg = "invalid plugins configuration: " .. err}
         end
+        local ok, err = utils.check_duplicate_key(conf_plugins_copy, conf.username)
+        if not ok then
+            return nil, {error_msg = err}
+        end
     end
 
     if conf.group_id then
diff --git a/apisix/admin/credentials.lua b/apisix/admin/credentials.lua
index 3622867528d8..73e877d8b0e8 100644
--- a/apisix/admin/credentials.lua
+++ b/apisix/admin/credentials.lua
@@ -18,20 +18,29 @@ local core     = require("apisix.core")
 local plugins  = require("apisix.admin.plugins")
 local plugin   = require("apisix.plugin")
 local resource = require("apisix.admin.resource")
+local utils = require("apisix.admin.utils")
 local pairs    = pairs
 
-local function check_conf(_id, conf, _need_id, schema)
+local function check_conf(id, conf, _need_id, schema)
     local ok, err = core.schema.check(schema, conf)
     if not ok then
         return nil, {error_msg = "invalid configuration: " .. err}
     end
 
     if conf.plugins then
+        -- check_schema encrypts the key in the plugin.
+        -- check duplicate key require the original key.
+        local conf_plugins_copy = core.table.deepcopy(conf.plugins)
         ok, err = plugins.check_schema(conf.plugins, core.schema.TYPE_CONSUMER)
         if not ok then
             return nil, {error_msg = "invalid plugins configuration: " .. err}
         end
 
+        local ok, err = utils.check_duplicate_key(conf_plugins_copy, nil, id)
+        if not ok then
+            return nil, {error_msg = err}
+        end
+
         for name, _ in pairs(conf.plugins) do
             local plugin_obj = plugin.get(name)
             if not plugin_obj then
diff --git a/apisix/admin/utils.lua b/apisix/admin/utils.lua
index eee2787f0540..594840a1075e 100644
--- a/apisix/admin/utils.lua
+++ b/apisix/admin/utils.lua
@@ -19,6 +19,8 @@ local ngx_time = ngx.time
 local tonumber = tonumber
 local ipairs = ipairs
 local pairs = pairs
+local consumer = require("apisix.consumer")
+local plugin = require("apisix.plugin")
 
 
 local _M = {}
@@ -110,4 +112,51 @@ function _M.decrypt_params(decrypt_func, body, schema_type)
     end
 end
 
+
+local plugin_key_map = {
+    ["key-auth"] = "key",
+    ["basic-auth"] = "username",
+    ["jwt-auth"] = "key",
+    ["hmac-auth"] = "key_id"
+}
+
+
+function _M.check_duplicate_key(plugins_conf, username, credential_id)
+    if not plugins_conf then
+        return true
+    end
+
+    for plugin_name, plugin_conf in pairs(plugins_conf) do
+        local plugin_obj = plugin.get(plugin_name)
+        if not plugin_obj then
+            return nil, "unknown plugin " .. plugin_name
+        end
+
+        if plugin_obj.type ~= "auth" then
+            goto continue
+        end
+
+        local key_field = plugin_key_map[plugin_name]
+        if not key_field then
+            goto continue
+        end
+
+        local key_value = plugin_conf[key_field]
+        if not key_value then
+            goto continue
+        end
+
+        local consumer = consumer.find_consumer(plugin_name, key_field, key_value)
+        if consumer and
+            ((username and consumer.username ~= username) or
+             (credential_id and consumer.credential_id ~= credential_id)) then
+            return nil, "duplicate key found with consumer: " .. consumer.username
+        end
+
+        ::continue::
+    end
+
+    return true
+end
+
 return _M
diff --git a/t/admin/consumers2.t b/t/admin/consumers2.t
index 6e351d02be96..ac9adb04a6fc 100644
--- a/t/admin/consumers2.t
+++ b/t/admin/consumers2.t
@@ -174,3 +174,86 @@ __DATA__
     }
 --- response_body
 {"error_msg":"wrong username"}
+
+
+
+=== TEST 6: create consumer
+--- config
+    location /t {
+        content_by_lua_block {
+            local t = require("lib.test_admin").test
+            local code, body = t('/apisix/admin/consumers',
+                ngx.HTTP_PUT,
+                [[{
+                     "username": "jack",
+                     "desc": "key-auth for jack",
+                     "plugins": {
+                         "key-auth": {
+                             "key": "the-key"
+                         }
+                     }
+                }]]
+            )
+        }
+    }
+--- request
+GET /t
+
+
+
+=== TEST 7: duplicate consumer key, PUT
+--- config
+    location /t {
+        content_by_lua_block {
+            local t = require("lib.test_admin").test
+            local code, body = t('/apisix/admin/consumers',
+                ngx.HTTP_PUT,
+                [[{
+                     "username": "jack2",
+                     "desc": "key-auth for jack2",
+                     "plugins": {
+                         "key-auth": {
+                             "key": "the-key"
+                         }
+                     }
+                }]]
+            )
+
+            ngx.status = code
+            ngx.print(body)
+        }
+    }
+--- request
+GET /t
+--- error_code: 400
+--- response_body
+{"error_msg":"duplicate key found with consumer: jack"}
+
+
+
+=== TEST 8: update consumer jack
+--- config
+    location /t {
+        content_by_lua_block {
+            local t = require("lib.test_admin").test
+            local code, body = t('/apisix/admin/consumers',
+                ngx.HTTP_PUT,
+                [[{
+                     "username": "jack",
+                     "desc": "key-auth for jack",
+                     "plugins": {
+                         "key-auth": {
+                             "key": "the-key"
+                         }
+                     }
+                }]]
+            )
+
+            ngx.status = code
+            ngx.say(body)
+        }
+    }
+--- request
+GET /t
+--- response_body
+passed
diff --git a/t/admin/credentials.t b/t/admin/credentials.t
index 15119829c2e3..6d15f9288cc7 100644
--- a/t/admin/credentials.t
+++ b/t/admin/credentials.t
@@ -110,7 +110,7 @@ passed
                      "desc": "basic-auth for jack",
                      "plugins": {
                          "basic-auth": {
-                             "username": "the-user",
+                             "username": "the-new-user",
                              "password": "the-password"
                          }
                      }
@@ -119,7 +119,7 @@ passed
                     "value":{
                         "desc":"basic-auth for jack",
                         "id":"credential_a",
-                        "plugins":{"basic-auth":{"username":"the-user","password":"WvF5kpaLvIzjuk4GNIMTJg=="}}
+                        "plugins":{"basic-auth":{"username":"the-new-user","password":"WvF5kpaLvIzjuk4GNIMTJg=="}}
                     },
                     "key":"/apisix/consumers/jack/credentials/credential_a"
                 }]]
@@ -492,3 +492,99 @@ GET /t
 --- error_code: 400
 --- response_body
 {"error_msg":"missing credential id"}
+
+
+
+=== TEST 17: create a consumer bar
+--- config
+    location /t {
+        content_by_lua_block {
+            local t = require("lib.test_admin").test
+            local code, body = t('/apisix/admin/consumers', ngx.HTTP_PUT, [[{ "username": "bar" }]])
+        }
+    }
+--- request
+GET /t
+
+
+
+=== TEST 18: create a credential with key-auth for the consumer bar
+--- config
+    location /t {
+        content_by_lua_block {
+            local t = require("lib.test_admin").test
+            local code, body = t('/apisix/admin/consumers/bar/credentials/credential_c',
+                ngx.HTTP_PUT,
+                [[{
+                     "desc": "key-auth for bar",
+                     "plugins": {
+                         "key-auth": {
+                             "key": "the-key-bar"
+                         }
+                     }
+                }]]
+            )
+        }
+    }
+--- request
+GET /t
+
+
+
+=== TEST 19: can not create a credential with duplicate key
+--- config
+    location /t {
+        content_by_lua_block {
+            local t = require("lib.test_admin").test
+            local code, body = t('/apisix/admin/consumers/bar/credentials/credential_d',
+                ngx.HTTP_PUT,
+                [[{
+                     "desc": "key-auth for bar",
+                     "plugins": {
+                         "key-auth": {
+                             "key": "the-key-bar"
+                         }
+                     }
+                }]]
+            )
+
+            ngx.status = code
+            ngx.print(body)
+        }
+    }
+--- request
+GET /t
+--- error_code: 400
+--- response_body
+{"error_msg":"duplicate key found with consumer: bar"}
+
+
+
+=== TEST 20: can update credential credential_c with same key
+--- config
+    location /t {
+        content_by_lua_block {
+            local t = require("lib.test_admin").test
+
+            -- update desc, keep same key
+            local code, body = t('/apisix/admin/consumers/bar/credentials/credential_c',
+                ngx.HTTP_PUT,
+                [[{
+                     "desc": "new description",
+                     "plugins": {
+                         "key-auth": {
+                             "key": "the-key-bar"
+                         }
+                     }
+                }]]
+            )
+
+            ngx.status = code
+            ngx.say(body)
+        }
+    }
+--- request
+GET /t
+--- response_body
+passed
+--- error_code: 200
diff --git a/t/secret/aws.t b/t/secret/aws.t
index ae0e09b63398..c0d7266da762 100644
--- a/t/secret/aws.t
+++ b/t/secret/aws.t
@@ -314,3 +314,5 @@ GET /t
     }
 --- response_body
 all done
+--- error_log
+failed to fetch secret value: no secret conf, secret_uri: $secret://aws/mysecret/jack/key
diff --git a/t/secret/gcp.t b/t/secret/gcp.t
index b7fc5331cf37..dc28ab56ec65 100644
--- a/t/secret/gcp.t
+++ b/t/secret/gcp.t
@@ -247,6 +247,8 @@ kEJQcmfVew5mFXyxuEn3zA==
     }
 --- response_body
 all done
+--- error_log
+failed to fetch secret value: no secret conf, secret_uri: $secret://gcp/mysecret/jack/key
 
 
 
diff --git a/t/secret/secret_lru.t b/t/secret/secret_lru.t
index 3ff3386fcf15..9f320ae2883e 100644
--- a/t/secret/secret_lru.t
+++ b/t/secret/secret_lru.t
@@ -96,3 +96,5 @@ GET /t
     }
 --- response_body
 nil
+--- error_log
+failed to fetch secret value: no secret conf, secret_uri: $secret://vault/mysecret/jack/auth-key