Activation ID's and backup servers

Hello. I have a question about activating our FreePBX installations and us maintaining our backup servers like we currently do. As I understand, the activation ID’s are tied to a particular set of hardware. However, we have several sets of servers that are carbon copies of each other so we can place one online if another one is having an issue.

What issues would we run into if we register a FreePBX server, but then need to backup and restore to another set of hardware as a hot backup?

Would we need to register each installation with its own activation ID?

Any other info I should be aware of as far as the activation ID or registering?

Thanks in advance.