I've heard that has occurred and been dealt with at the chief pilot level. Usually the senior-to-both-original-guys pilot making those last-minute calls are well-known weasels (I can think of at least one myself), and often the once-senior-and-now-junior guy will just call in sick...right before the anticipated call from crew scheduling to release the senior guy.

Let's face it, sometimes we are our own worst enemy, and some guys just deserve a blanket party.