HI Richard, nice to meet you. Thank you very much for offering help to people, it's part of what makes WikiTree great :)
We try not to create duplicates; it seems they simply disappear and it's a non issue when merged but actually it creates behind the scene potential issues. One is that it actually keeps the old number active and re-directs any traffic to the new profile. This becomes more complicated when family are linked. It also uses up that id# making it forever unavailable for re-use.
The last name at birth (lnab) can be changed by a profile manager. Even this is to be done only after careful deliberation and with reasonable surety.
Collaboration is the route to take. It's best to contact the profile manager with your information and have them change the lnab, or to become a manager and do it yourself after communicating with the other profile managers.
I hope this makes sense and is helpful. Glad to have you here.