Well, my GCC has 4 toes, and a nail on each of those 8 toes ... I am not sure that this would be a deal breaker for me as birds can adapt. What WOULD be a concern would be how that baby lost those other two toes ~ if it was a birth defect then that's not an issue and the baby will adapt (can still grip and perch with 3 toes). If the parents attacked the baby and bit off a toe or two, well, then I would have to look more closely at the environment in which the breeders are kept and make a decision after that ...
I hope that it's just a birth defect, and if you can get a good look at the feet you should be able to tell just by looking. If that's the case, then there isn't an issue at all and you just have a "special" birdy.
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