I served in Ramadi with twin sisters.
They promoted one to E-5 so people could tell them apart - the ONLY reason she was promoted.
And each one was dumber than her sister.
They were in the same National Guard brigade, same company, same staff section, same building, same shift. They could not and would not be separated - and anyone who complained was wall-to-wall counseled by the home base command.
I went through basic training with a set of identical twins.
The drill sergeants had fun - because they could feign ignorance of the other brothers existence, when a new “shift” came on board.
“Didn’t I tell you to clean the orderly room? Why are here at the mess hall?”, much hilarity ensues. They were assigned separate duty stations but the DS’s figured out a way to ensure their orders were changed prior to that. (One of the brothers “failed” a PT test, and got held over)