Here is a side by side comparison of the two Dismember: Massive Killing Capacity patches that are out there, to help people distinguish between the two.
The vintage patch is on the left, notice how shiny the thread is with hints of silver. On the right is the re-issue / bootleg (I'm still not sure what it is exactly), which is a tad smaller and slightly less detailed. It is easy to confuse these two while staring at blurry eBay photos. The easiest way to tell is by looking at the crosshairs on the skeleton's forehead: the vintage patch has two rings, while the re-issue only has one ring.
All said and done, the boot/re-issue is quite well done and had me fooled for years!