Crested Gecko Tail Biting?

I have two young cresteds and I noticed today that one of them has started biting the end of the others tail and I've had to "rescue" the one being bitten twice now (I'm currently looking for something to put one of the in for the night until I can get a proper cage tomorrow).

Is this normal for young cresteds? These are the first babies I've had, they're a little bigger than hatchling size I think, all my others I got at sub adult size and my two girls have never had a problem. Here are some recent pictures of the two to give an idea of about how old they are

The bully:


The bullied:

Could be two males. How young are they? I don't suppose they've been sexed yet, have they?

Its possible that they're males, I'm not entirely sure how to sex them at this age

Pretty sure they're males. You should house them separately just to be safe.

That's the plan, one of them is in a critter keeper for the night until I have a chance to get a proper tank in the morning.

I was really just asking because I was curious if this is a common behavior in young cresteds or not

I have two juvenile cresteds, have had them for about a couple of months now. They get along perfectly in my medium exo-terra, but I'm pretty sure they're both female. In fact, I've seen them on several occasions laying right next to each other in one of the toilet paper tubes.

Thanks. These guys had been together for about 3 months or so and seemed totally fine until today. I'm not sure how much time they spent near one another though since the cage has a ton of plants and stuff to hide in, but I know my girls do spend a lot of time hanging out together