Is it common or worth anything to find 2 bills that were printed one after another? For example... one is serial # 11111111 the other is 11111112
Yes, it is not uncommon to obtain two or more notes in sequence. I typically get consecutive $1 banknotes in change, and some banks even distribute consecutive $20 notes. Depends what year the note was printed also- I have 3 consecutive 1976 $2s, which you most likely won't find today. $2 notes from 2013, however, are incredibly easy to find (it's almost impossible to find $2 notes that are not consecutive).
other than binaries ans such, one can obtain strapped money from their bank/cu, which would be one hundred consecutive serial numbers. I've never bought a "block" which could technically be a whole bunch of consecutives.