If you want to, I don't see why not. Sibling breeding isn't going to give you an issue unless you keep doing it generation after generation.
I know reptiles can handle inbreeding pretty well, and so can rodents. I've been doing my own experiment with rats. Sib to sib, father daughter, son mother, etc. So far no issues and I doubt I will run into anything at this point. There was a study done on mice. It took 15 generations of sib to sib before anything weird started showing up. I'm guessing reptiles would be similar to that experiment considering they aren't roamers and would come in contact with family members quite often in the wild.
Also, if you want to do it, do it! Don't let anyone hold you back. Plenty of morphs were created/found by people just like you who bred things no one else thought to breed. You're not going to have a problem getting rid of a clutch of normals. Bp clutches aren't that big.
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