diff --git a/evennia/comms/comms.py b/evennia/comms/comms.py
index b9a308c350..e6ee5eef8c 100644
--- a/evennia/comms/comms.py
+++ b/evennia/comms/comms.py
@@ -396,7 +396,8 @@ class DefaultChannel(ChannelDB, metaclass=TypeclassBase):
                 to build senders for the message.
             sender_strings (list, optional): Name strings of senders. Used for external
                 connections where the sender is not an account or object.
-                When this is defined, external will be assumed.
+                When this is defined, external will be assumed. The list will be 
+                filtered so each sender-string only occurs once.
             keep_log (bool or None, optional): This allows to temporarily change the logging status of
                 this channel message. If `None`, the Channel's `keep_log` Attribute will
                 be used. If `True` or `False`, that logging status will be used for this
@@ -428,7 +429,7 @@ class DefaultChannel(ChannelDB, metaclass=TypeclassBase):
         if not msgobj:
             return False
         msgobj = self.message_transform(
-            msgobj, emit=emit, sender_strings=sender_strings, external=external
+            msgobj, emit=emit, sender_strings=list(set(sender_strings)), external=external
         )
         self.distribute_message(msgobj, online=online)
         self.post_send_message(msgobj)