hi good morning
I'd like to help are you there?
Having twins myself, around the same age, I can relate to what you are going through. Much of what children that age, and twins in particular, with their parents deal with is attention seeking. I'd say you are absolutely correct in that the one twin is looking for whatever attention they can get.
my daughter is very similar in her behavior. what we try and do is instead of giving her the attention that she is seeking (pos or neg), we put her in time out for a short time out for a minute or two, ask them to apologize and teach them the correct behavior. I see that you've tried similar, but we try not to make the time-out something that gives them the attention they are looking for.
it does take time and effort, and I can't say that my daughter hasn't stopped, but she certainly has improved. she has good days and bad days.
I'm sorry that you rated my response, which we were in the middle of conversing about, as poor. If there is any way I could help you further please ask. I was not able to fully complete our discussion.
Have a good day and good luck.