I have noticed that players check in on punts and kickoffs as "wearing another number". Ironically, I've only noticed this during KState games.

The obvious reply is because two guys are wearing duplicate numbers on the field at the same time, but that's not the case. And, they're not checking in as an eligible receiver, or anything, so I don't know why the referee announces "number five is checking in as number 82" or "number 4 is now wearing number 87". It's not like the guy changed his jersey.

Anyone able to shed light on this?