Yet another clone/licensing question (identical hardware)

Machine A is a Win7 Pro OEM that has a failing mb that needs to be sent for repair. Machine B is also a Win7 Pro OEM with identical hardware. Any problems if I Acronis-clone/move Machine A's drive to Machine B then change the license to Machine B's native license? Looking for the easiest way for temp usage of Machine B by Machine A's user during the 2-3 weeks when the mb is being repaired.

The Win7 Pro OEM licenses were not factory preinstalled - just the "for use with a new computer" variety. There are no other machine/user specific licenses in use.

I've been though a zillion posts about cloning and am now so confused... SysPrep seems like overkill and loses all the user specifics.

Are you talking about transferring the system (Windows installation) now on the hard drive in Machine A to the hard drive in Machine B, through a cloning or imaging process?

Or do you mean physically installing the hard drive from Machine A into Machine B?

Is there any chance that the motherboard will be unrepairable and need to be replaced? I assume this is being done under a warranty?

Not touching the existing drive in machine B as it will be placed back to "normal" use later. Most likely I would make an Acronis-clone of Machine A's SSD on to another SSD for use in Machine B.

Yes, this would be warranty work. The HDMI port stopped working although all other video ports are ok. FWIW, it's an Asus AMD APU box. It is always possible that a replacement mb would be returned. As I understand, if that is the case, I'd have to tell MS the situation and I should be able to reassign Machine A's Win7 license to the new mb.