I also think it is difficult to develop two catchers in the major leagues at the same time. I don't want to go all O L D - S C H O O L, but most teams tend to have a established catcher / a promising back up or a promising starter / established backup (if I am wrong, someone let me know, I am going off memory here). I think the Jays really didn't know what they had in either, they probably suspected Jansen was better but still with both knocking on the door and the current circumstances they said "f*** it, lets see".
It'll be interesting to see how Kirk does now that he's up with the team too. This season certainly isn't boring.