mailchimp api when moving member to new audience, member is not removed from old audience

When using the Mailchimp 3.0 api, if I move a member to a new list/audience using the ‘add or update list member’ endpoint, the old instance of the member is not removed from the old audience.

First I tried updating a member to a new group using the ‘add or update list member’. This resulted in there being the same member in 2 audiences. Next I tried retrieving all users from the other list, then checking if the user I wanted to add to a new group was found in there. Then remove that user from the old list and add the new member to the right audience. The problem with this is that the old user gets archived and cannot be added back using the same api call as before when the user is changed back to the old audience.