fix matcher decos

nonebot/matcher.py

@@ -109,14 +109,15 @@ class Matcher:
     def receive(cls) -> Callable[[Handler], Handler]:
         """接收一条新消息并处理"""
 
-        def _decorator(func: Handler) -> Handler:
-
         async def _handler(bot: Bot, event: Event, state: dict) -> NoReturn:
             raise PausedException
 
         if cls.handlers:
             # 已有前置handlers则接受一条新的消息，否则视为接收初始消息
             cls.handlers.append(_handler)
+
+        def _decorator(func: Handler) -> Handler:
+            if cls.handlers[-1] is not func:
                 cls.handlers.append(func)
 
             return func
@@ -131,8 +132,6 @@ class Matcher:
         args_parser: Optional[ArgsParser] = None
     ) -> Callable[[Handler], Handler]:
 
-        def _decorator(func: Handler) -> Handler:
-
         async def _key_getter(bot: Bot, event: Event, state: dict):
             if key not in state:
                 state["_current_key"] = key
@@ -152,6 +151,9 @@ class Matcher:
             # 已有前置handlers则接受一条新的消息，否则视为接收初始消息
             cls.handlers.append(_key_getter)
         cls.handlers.append(_key_parser)
+
+        def _decorator(func: Handler) -> Handler:
+            if cls.handlers[-1] is not func:
                 cls.handlers.append(func)
 
             return func