I think it's incredibly rude to reject gifts... my wife once got me a copy of Transformers Devastation (can't remember the exact issue) and at the time she didn't realise that I have a standing order with my comic store (I've had that standing order since G1!!). So of course, I ended up with a double of that issue (I'm gonna give my double to mel as soon as I can get off my butt and mail it to her ).

About 10 years ago a mate of mine bought me Transmetal Tarantulas. I already had it, so I repainted it as "Vok Hunter Tarantulas" (note this was well before the "official" Fox!Kids repaint came out). Most doubles I get as gifts I keep mint in package and display them that way. I have a MOSC Energon Perceptor and Armada Sideswipe - both gifts of figures I already had, so I just display them sealed.

But uh... yeah. I'd keep it. *shrug*