Different tmux configs for different sessions

From https://github.com/zolrath/wemux:

wemux enhances tmux to make multi-user terminal multiplexing both easier and more powerful. It allows users to host a wemux server and have clients join in either:

Mirror Mode gives clients (another SSH user on your machine) read-only access to the session, allowing them to see you work, or

Pair Mode allows the client and yourself to work in the same terminal (shared cursor)

Rogue Mode allows the client to pair or work independently in another window (separate cursors) in the same tmux session.

It features multi-server support as well as user listing and notifications when users attach/detach.

It is a shellscript wrapper over tmux - no compiling necessary.

Given the code you've posted, if you run ssh from within tmux, you'll have $TERM = screen, so you won't be trying to attach to a tmux window. In other words, the code you already have should work as desired. There's something fishy going on. Make sure your dot files don't mess up the TERM variable (if you need to modify TERM, which is very rare, make sure to do it only in very specific circumstances; in particular don't change it if it's screen).