So a slight tangent, but possibly related as this is the 2nd instance I've heard of this month where a 2nd reservation was somehow generated on the spot by a front desk associate...

Note this was an Aloft and we were traveling on business, not a points stay.

A co-worker had checked in and almost immediately lost his room key. He went to the front desk for a new key, then went to his room and all seemed fine. The next day, via credit card txt alerts, he found the hotel had charged 2 different credit cards. Luckily we were still at the hotel and my co-worker had an absurd exchange with an indigent front desk manager.

Initially the FD manager all but called my co-worker a lier, then was unable to find a 2nd reservation despite much key tapping, he finally relented and searched by some alternate means to discover that a 2nd reservation did indeed exist. After comparing the two reservations the manager concluded that the FD associate somehow created the 2nd reservation when attempting to create a replacement room key. The manager removed/canceled one of the reservations, refunded the associated charges, and apologized for his behavior. He also mentioned that employees were still getting used to the new computer system.

TLDR: It seems a change in the FD computer system allows for easy/accidental/unintended generation of new reservations.

Theory: It is possible the OP's friends encountered this issue when they attempted to check-in under OP's reservation. A 2nd reservation was accidentally generated upon check-in and the OP's reservation did eventually get flagged as a no-show.