Here's a project for us non-Moderators:
The tag wiki of the latter currently states:
Multi-user is a term that defines an operating system, computer program, or a game that allows use by more than one users of the same computer at the same time. Android 4.2 Jelly Bean brought multi-user support to Android tablets.
Here's the project: Go through each of the (currently) 21 questions tagged multiple-accounts and retag them appropriately. At the very least, anything that is tagged multiple-accounts and multi-user the former is redundant and should be removed. Also, if there are other issues with the question, fix those too.
Once cleaned up to the degree possible we can either let the tag die, set it as a synonym, or, if there are still some questions using it, define an appropriate wiki definition.