About "banning a Block Block", basically yes, you shouldn't be allowed to combine any two same cards, not only Blocks. This feature meant to be used to merge two different actions into one card, not to double-strengthen the only one certain.
Yep, I'm working on a patch right now which disallows combining of the same card. I think this will encourage more fun experimental gameplay and removes the simple strategy of block + block = win :P
