Logic Pro 9 Undo branch


How do you go back to an undo branch?
I had been working a while when I noticed the midi drum track had gotten on the bass track. I want to go back to where the drum was in the correct track, copy the bass and drums, and then go back to the last place I was and paste the bass and drums. That way I don't lose all the work I did before I noticed. When I went back, I accidentally moved something and undid. It now appears that there is no way back "down" to where I was when I noticed the problem.
Aren't there undo branches in Logic, like in DP?