Well, it is quite possible that neither Perk, nor BBD will get what they want come this summer. If Doc goes with a 3 man rotation at the 5 spot, it's going to keep Perk's numbers down. Moreover, it will force BBD to play exclusively at the 4, where his minutes will be dramatically cut. If this occurs, both may get far smaller offers than they anticipate.
Assuming they both do get substantial offers, though, I think the bigger debate is whether we'd want to ever try to keep both. While I think both could potentially start on a future Celtic contender, I don't see them being effective together. For that reason, I'd be hesitant to sign both.
However, on the other hand, there probably is something to be said for holding on to both as future trade assets. Still, that worries me. Will Baby and Perk both deflate their value once they're forced to play bigger minutes without being surrounded by Hall of Famers?