First, Some Details:
I have two young adorable little cockatiels named Schala and Janus. They are very sweet and ridiculously human friendly.
They are less than a year old and only 5 days difference in age (they will be 1 in 5 months).
They are born from the same breeder and have the same mother and father.
When they were born, they each shared a cage with many multiple other cockatiels (all siblings of about the same age), but not each other (there were two cages both with multiple other 'tiels. Schala was in one, and Janus in the other).
They have always shared a cage together since I have had them (they were little more than one month old when I got them).
Schala is your traditional yellow and grey 'tiel while Janus is grey and white (his face will eventually turn white, I am told).
I am not sure of the true gender of either bird.
They do vie for my attention almost exclusively, despite spending most of their time together.
They get frustrated with each other sometimes, when one tries to take the other's spot on their perch or my shoulder. By frustrated, I mean that they will squawk a bit and clash beaks with their mouths open. They do this to try to be intimidating to the other one, but I have never seen either one of them try to do the other one any serious harm.
I came home one day and noticed that Schala had a small hole on her beak (about halfway between the sizes of an ant and a ladybug [sorry struggling with something to compare the size to]). It's on her right side, just under the cere, and my first thought was that they fought and Janus got the best of her.
Schala shows no sign of pain, she doesn't favor it or shy away if you try to touch it. Her behavior has been perfectly normal since we have been watching it (it has been about 3 days). It hasn't gotten any worse, any bigger, or changed any color (there is no red or anything, just a small dark hole). Other than the hole itself, there are no other negative signs. She has no trouble getting around, drinking, or eating. I don't think the hole goes all the way through, but it's very hard to tell because it is dark and she doesn't like holding her head still for very long.
I would be devastated if anything happened to either one of them, but I'm not sure what to do. I don't want to end up taking her to the vet if it's nothing (especially if she gets scared, knowing how fatal stress can be for birds).
I thought about getting a divider cage, so that they could still be close, not get lonely, but still be forced to respect each other's boundaries.
Is there any chance that this hole could be caused by anything other than her sibling?
Will it ever grow back?
What should I do to best ensure the health of my sweet little 'tiel and hopefully the healing of this little cavity?