What do U.S Military dog tags say on the second one?

Umm... They usually both have the same info. I've never been deployed, but from what I understand is that when someone dies one dog tag is taken back so that accountability of that person can be had while the other one is left with the body to identify it later. The marines I know usually have one in their boot in case they loose their head/ upper torso the rest of them can still be identified.