this is exactly what happened. I tested itSounds more like it's just because they're dying in Moradon; there's probably nothing preventing coin gain/loss there on DOT deaths.
The game's a complete mess; they've implemented death handling code, manually, for each and every place they can die. Not all of them are consistent, so it really doesn't surprise me that they'd screw up.
TRWTF is that the DOT isn't being reset on zone change. The old source & all various official server files I have all handle this correctly, which... means somewhere along the line they've broken this feature that's worked from the very start. :/