I'm no .vmdk expert, but it looks rather wrong to me too. Won't that send reads and writes for sector 2930266584 of the virtual disk to sector 0 of \\.\PhysicalDrive8, accessing (or clobbering) whatever was at virtual sector 0 before? If true, you'd end up with a disk that works until you try to access beyond the half-way point, at which point it would wrap all accesses back to the start. Catastrophic data loss would be quite likely.
If you need to represent the disk as two extents, my guess is that you would want something more like this:
RW 2930266584 FLAT "\\.\PhysicalDrive8" 0
RW 2930266584 FLAT "\\.\PhysicalDrive8" 2930266584
so that I/O on the second extent of the virtual disk will end up sent to the correct location on the physical drive.
Of course, since we don't actually support this configuration at this time, we won't know if anything that looks like it works will actually be reliable and always send I/Os to the correct places... Whatever solution might be proposed for this problem, it'll be the OPs responsibility to test it thoroughly enough to satisfy themselves that they're not about to lose all their data...
Cheers,
--
Darius