Because each team provides the footballs they use on offense. So the Colts use one set, and the Patriots use another set.
(And to add one note, Grampa Dave...only the Patriots footballs were deflated, not the Colts -- well at least 11 of the 12 were...which made me wonder why the media even devolved into covering the coldness angle, which might contribute very slightly to air loss...also 'twas 51 at game-time...not exactly brutally cold...or we would have seen snow...and not rain during the game)
Thanks for the feedback. I was not aware that each team provided the balls for their offense.
A relative has since told me that apparently each punter and field goal kicker provide and use their own balls. He said that the league has known about this forever. That means that the QB, punter and field goal kicker/kickoff guys have been able to customize the balls they use re psi and outside texture.