Oh my I could have written this post exactly myself.
My boys are 5 and 3.5 and share a room/bunks and their bedtime is 7pm give or take a few.

We do exactly the same routine! Our boys will chat to each other, dare the other to do something, say they need to wee 5 times and yell out for DH or myself and finally get to sleep by 7.45-8is.

Honestly we just get to the point where we are putting them back to bed over 5 times a night.
Ahhhh!
I look forward to trying all suggested solutions
.