Hm. I can't find anything at all when I searched. UTComp might fit the bill but it's a rather large one to get just to get everyone back to their respective teams. That's a pretty good question though. Remember that players can choose their preferred team in the Options if that helps.
Your prime sources for pretty much all maps are:
Unreal Playground
UZ2 Files
Mapraider
To get the files out of those UZ2 packages, you can use ucc.exe. But that's honestly a pain in the arse.
Instead, use UZTool.
And, last but kinda least, use Google if all else fails you.
If you have any questions, let me know.
Another reason for me to learn uscript I guess? Any team related mutators are to make "even" teams or whatever, but for my purposes the teams are already set before anyone even joins, so having same teams the second map would speed things up a bit.