So are there multiple tamriel rebuilts? And do they have their own starts? Thanks for any answers.

http://tamriel-rebuilt.org/ - the one and only. There are several other province mods, but only TR is fully playable (i.e. with big landmass, quests, blackjack and hооkers) at the moment.

There is only one TR team.
This is the curent thread, with all the links for downloading: http://www.gamesas.com/topic/1469832-relz-tamriel-rebuilt-sacred-east-15-6/

To clarify: the http://tamriel-rebuilt.org/project is the oldest project, but is only focused on rebuilding the province of Morrowind these days. There are other projects, like http://provincecyrodiil.project-tamriel.com/index.php?sid=f8c4a12cf63cb309a54148625963c612or http://daryam.com/skyrim/forums/index.php?sid=b55051a43824df4367b9da1a87c8bd6f, that are independent from Tamriel Rebuilt, though the different province mods have similar quality requirements, coordinate their borders and often have the same modders working on them. Tamriel Rebuilt has released a large piece of land already, while Cyrodiil and Skyrim have both released a playable teaser/alpha.

there's only one tamriel rebuilt, but they've released multiple maps, if that's what you meant.

And these multiple maps are always all integrated into the latest one. In other words: don't let the term "multiple maps" fool you, there's only one download for all the released landmass.