If they are both OPN 1s, or both OPN 2s, or both OPN3s, I am pretty sure it doesn’t matter. My two OPN 1s appear to be identical. For warranty purposes they may be registered as right and left, but functionally they are the same. Mine were purchased thru TruHearing and my audiologist needed to tell TruHearing which serial number went with which ear. I believe Genie 2 software just reads the serial number based on how the cables are hooked up. If different than the original reading (cables got switched), the software will warn you. So likely, warranty might be your only (but big) concern.