FWIW, one time I had several res show up in my account. Got the e-mail confirmations.

Had no idea where they came from.

Went online and canceled them as it was the week-end.

Call Marriott the next week and asked them what was going on. Apparently if an agent doesn't complete clear the information from the last member to call they can accidentally book it under the wrong MR#.

Similarly, I had a Ritz Carlton in China cancel a res I had in the US. Apparently the front desk clerk had fat fingered the MR # for someone canceling at their property and they wound up wit my number.

So your situation does not shock me.