Basically, one of our clients replaced a down AP (AP1) with another AP from a decommissioned network (AP2). The catch is that the client requires historical data be kept for all nodes, regardless of whether or not they're part of an old network that's been taken down.
To clarify:
When we did the change, AP1 was showing as down and AP2 was showing as up with mismatched config (AP2's name etc. had already been changed on the controller). Then we did a device replacement on AP1 and selected AP2. This got rid of AP2's entry and AP1 then showed as up with its own history.
Ideally, we wanted to have some way to change the MAC of AP1's entry so we can keep AP1's data while still keeping AP2's data as some sort of archived entry (despite the confliction MACs).
From what you're saying that's not really possible and the data from AP2 is just gone.