I ordered a light and it came with the worng tombstone for it. I have a bunch of single pin bulbs and wanted to know if I could change the tombstones to match my bulbs?

So what's not right? The lamps, or the sockets?
You cannot just change from bi-pin to single pin. The ballast is different.

Single pins are for High Output (H.O.)fixtures, generally found in commercial applications. If you are thinking of changing ballasts, make sure they operate on your building's voltage

Single pins are for High Output (H.O.)fixtures, generally found in commercial applications. HO fluorecents use bi-pin sockets. The two pins are encased in black phenolic on the lamp ends.