It is possible, as I'm in the process of doing it. The original M2.NVME is a short one, I began by removing it as I could see the original short screw stand off could be unscrewed, leaving one for the standard longer length M2 drives. I thought I'll put the short M2 drive in the 2nd slot (higher up) but then noticed that stand-off wasn't in the right place either. Then I noticed the unused higher up slot stand-off could be slid right, removed and there was the same clamp system to the left where the stand-off could be resituated.

I now have 2 M2.NVME drives in, cloned the smaller to the larger and can format the 2nd if I want.