It does get confusing doesn't it? I am pretty sure that the MaryMac some of us know from the radio is MaryMac90 and I think she is 2 of the other MaryMac's (the ones with locations). I have a feeling in the back of my mind that the one that is just "MaryMac" is a completely different person.
With regards to the duplicate memberhips, apart from Joe's reminder, surely it even creates hassle for the member who must have 2 or more sets of PMs to check if they are not to miss them.
Another Mary I can think of, and I think she is still around is "Sings Irish" - one of the 2 people to introduce me to Mudcat from the newsgroups I used to read (and still would if my ISP had a decent news server) - she and Jeri have a lot to answer for!