Two NVMe devices appearing as one

Question

When I run lsblk I see that I have two NVMe devices:

$ lsblk
NAME                   MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
...
nvme0n1                259:0    0   1.1T  0 disk  /home
nvme1n1                259:1    0   1.1T  0 disk

But df -h presents a single NVMe device with 2.2T of space:

$ df -h
Filesystem                  Size  Used Avail Use% Mounted on
...
/dev/nvme0n1                2.2T  551G  1.7T  25% /home

When I run strings on the two devices shows that they have the same data:

$ sudo strings /dev/nvme0n1 | head

$ sudo strings /dev/nvme1n1 | head

So it seems that somehow /dev/nvme0n1 and /dev/nvme1n1 are being merged together as a single device. What could be the cause of this?