Unless it was a long time ago, I think it was very unlikely to have been the Bootleg Beatles - they play considerably larger venues than that. Doesn't matter though - if you enjoyed the experience, what's not to like?
I was never a great fan of the idea of Tribute bands, but I must admit I'm coming round to the idea - probably a better experience than trying to watch two or three old men from the original band struggling to do what they did fifty years ago (even though they'll have a far superior sound system...