I thought I had a disk failing, but it ended up being the enclosure. In the process of figuring this out I added a new disk as a spare using the same enclosure. I then replaced the enclosure with a new 4 bay enclosure. Both the original disk and new disk are now connected to the system.
However the problem is that ZFS now reports "disk11" in two spots. Disk11 is the original disk and the new disk has been bumped to disk12.
How can I safely remove "disk11" from the spare pool? I am afraid it will remove disk11 from both spots. I was able to complete a scrub yesterday after the fiasco, so I'm not totally scared if both disks get removed, but would like to avoid it.