Unfortunately, that wasn't enough. When I created the Kindle version of this new anthology I've been talking about, Time Quadrants, I did a search on all Henry Melton titles in the Kindle Store. Up popped 11 entires. Two versions of each of the five novels, and the just released anthology.
Some time after I had revoked Amazon's permission to make their own copies of the novels, they had done so with my remaining novels. Tsk. Tsk.
So, following a pointer I dug up in the Amazon forums, I found the company's digitalrights email address and sent them a firm but polite email requesting that they remove the duplicates (and specifically listing their codes just to make sure). According to their auto-responder reply, they should get around to reading my email in 72 business hours (whatever that means) and maybe I'll get a response.
Until then, potential buyers have an additional problem. Amazon's converted versions are a few cents cheaper than mine (Amazon does like to play price games) but those versions have the DRM. It's also likely that any royalties due me from the converted versions will be caught in minimum-payment limbo and I'll never see them. All I can do is wait.