Posting this here in the hopes that someone, by some stroke of luck, has a workaround while I twiddle my thumbs and wait for VMware to actually get back to me with the details of my support entitlement which magically aren't available because "the system is down" when I call for support on a dead-in-the-water production system. 
I seem to have gotten myself into a little bit of a situation.
[root@esx01 ~]# esxcfg-volume -l VMFS3 UUID/label: 4bc639b4-21bbc059-d77b-e41f132c2a8a/shared-esxdev Can mount: No (duplicate extents found) Can resignature: No (duplicate extents found) Extent name: naa.600a0b800047f5f20000bc934bf1480e:1 range: 0 - 1279487 (MB) Extent name: naa.600a0b80006e09620000bc914bf14835:1 range: 511744 - 1535487 (MB) [root@esx01 ~]# esxcfg-volume -m shared-esxdev Mounting volume shared-esxdev Error: Unable to mount this VMFS3 volume due to duplicate extents found
Here's the background:
Our SAN is active-passive. I created two extents and load-balanced them between the two controllers on the SAN. At some point, I grew the extents -- this has been working fine in production for months. Today, we had some issues on our production SAN and had to fail over to some LUNs at our DR site, which have a different NAA ID than the old LUNs. Now, suddenly, VMware refuses to do anything with these LUNs whatsoever, apparently because the ranges for the extents overlap (even though they really don't). I can't mount or resignature them or do anything at all with them except watch ESX complain about them.
I have production data on these volumes, and I don't have the time to manually restore my VMs from file-level backups if I can avoid it. Help? 