No. It is assigned randomly when you first sign up for anything with AAMC. For many of us, it was MCAT prep material. If you ever bought anything from them, you already have an ID. It will follow you for the rest of your life. No relationship at all to SSN numbers, and no requirement to have a SSN.
Also, you are only allowed to have one. If you ever, for whatever reason, discover you have more than one, you need to tell them about it immediately and get it resolved. If you don't, multiple IDs could be used to commit fraud on either the MCAT or AMCAS applications (hiding unsuccessful application cycles, bad MCAT scores, or exceeding annual or lifetime MCAT limits). If discovered without you self reporting, if it was actually used to defraud a school or AAMC, you could be banned from ever applying to med school, and probably get yourself kicked out of any school, residency, or whatever you happen to be attending at the time of discovery.
