How about Tennessee? I could see them still thinking Vince Young is their man going forward, but I could also see them thinking that Cassel is a guy who has demonstrated that he's OK standing behind a more talented QB and that Vince is rapidly developing into a serious headcase, enough to threaten their push for a trophy or that they're too close to the prize to let Young screw things up again.
Think of it kind of like Manny Fernandez on the Bruins. In principle you really don't pay what Chiarelli paid for a backup goalie, but Boston's goalie situation is a little unconventional, and for the Niche that MFMF actually fills, which is a starting-capable insurance policy behind Boston's enigmatic starter, he's worth the price. Fernandez plays well himself and he pushes Thomas, which seems to be something Timmy really needs to stay focused. And if Timmy had turned into a pumpkin at any point over the last few months, MFMF could have taken over the starting job himself and the B's would probably still have won more games than they lost.
Of course you still run into the same problem, is that really worth two #1's? but Tennessee is right at the height of their playoff peak in the next couple years, and having a good #1a quarterback in case VY flakes out again really could be worth that to them right now. It's a bit of Yankee-think, but when you're close to a championship, overpaying a bit for that little bit extra tends to be something you consider. Collins isn't going to get you to the next level. He just doesn't have the tools. Cassel, especially the Cassel of the last 6 games or so when they really turned him loose, might.
EDIT: Clarity (probably still needs some)