Is combining different sources of complete protein bad for bodybuilding?

Can you answer curious.freak’s question about Bodybuilding?:

For those of you who like bodybuilding its commonly known that we need 6 meals per day to keep our body full of the required nutrients. My question is if there is something wrong with combing proteins from different sources, for example eating a TUNA sandwich with some CHEESE in it. Will the different amino acids cancel each other or anything downgrading the protein intake? Excuse me for my English , I hope I’ve been clear :P

Endurance Weight Training