Videos I didn't watch showing up on deck

Shows other users watch sometimes show the next episode up on deck for my user account, it’s lead to some confusion when trying to track progress on tv shows. Has anyone else experienced this or have suggestions?

1st:
If you have DLNA enabled, then every playback by a DLNA client on your network is ‘credited’ to the server owner, i.e. you.
This is because DLNA in general does not support user authentication. So plex has no means to distinguish who is actually watching the content.

2nd:
If you are using the trakt.tv plugin, you must create a filter in its preferences, so it only processes playback from you.