Hi, your bird is a male, his mutation is a normal grey, and his age is for sure under 1 year old. In the picture of June 22, he still has his yellow barred tails and a dullish colored head. So, I'd say he is for sure under 1 year old to about 1 year old.
Okay, that might be the reason. I find that when my male cockatiels are in the same cage as my females, they will both do heart wings to impress the females. Yeah, birds seem to like to copy other sounds. I have several cockatiels along with budgies and conures and they all try to copy each other. 😆