Unidentified Files

Well... Everytime I go into my Game folder I keep seeing some REZ files and then a copy of that file except directly underneath it there seems to be an awakward file ext. e.g. GUNS_M_PV_SR.rez.1.3a0d6fbc.5d4dc4e2.delta
I really have no idea what it does? Would something bad happen if I delete it? It's quite recent actually. I heard that it prevent somes REZ mods and if you delete it, you will automatically auto-patch whenever you open CA.
Ideas anyone?

SIDENOTE:
It doesn't happen to all the files just the major ones e.g. GUNS_M_PV_AR and GUNS_M_PV_SR.

It's the one they patched. The random hex looking stuff is just the file changing name thingy for when they are backing up. Etc etc etc Get it?