Having multiple accounts is in breach of the HH T&Cs.
Valid point.
Hilton is aware of Amex/Hilton practice to often open new honors accounts without user intervention and has a process to merge accounts of the same owner, even though the terms clearly says even just having the multiple accounts warrants cancelling all of them.
I was mainly mentioning the 4 rooms as a joke, though, referring to Amex ignoring the specified HH # on apps and creating duplicate accounts.