Marking territory, follow up

[Angcious]

I was interested in finding out more about if they really do mark their territory or not. I did a search where someone mentioned similar behavior that had me wondering, but it seemed there was doubt that it was actual territory marking. Has anything more conclusive come up about it?
I suppose it's a good guess that I really do have 2 boys, still haven't found sperm plugs though. My older one wants nothing to do with the younger one, chased after him a few times when I tried to let them come out together...even lunged at the door of his cage one time when I was pulling the younger one out of his own cage which is stacked underneath!
Anyway, my younger one rubs his head, neck or sometimes the side of his rump against things. It almost looks similar to the rubbing that they do at the beginning of a shed...only he does it when not shedding. Also, I never saw him do it in his cage, only when he's out. It's just 1 quick and casual rub, as if he quickly squeezed through a tight space. I've tried to get it on video but it's either too random or too quick for me to catch it.
But my older one has never done this. And it's kind of funny because he hates it when the younger one has free time before him. I thought it was a jealousy thing at first. He'll stare through his door and watch the younger one, never taking his eyes off of him and has the most PO'd look on his face the whole time. But when it's time for him to come out after, he doesn't seem to enjoy himself as much and is more likely to just stay near me. Otherwise, if he is first to come out, he's all over the place and having a ball.
I've wondered if he acts differently then because the younger one marked himself all over? But if that was the case, wouldn't that trigger my older one to want to do it too, but he doesn't?

[BlueyNoob]

I've hear tale of 'jealous' skinks, some refusing to come out if the other was first. Couldn't say myself, I only have one BTS and he loves his cuddles even if the other pets are being pet too.