I've had trouble with such revenants. Really annoying when you've tried and deleted a bunch of quickie 'test renders', only to have them pop up again. And, yes, sometimes push a couple of 'good renders' off end of list into oblivion...

I've found that if you use Poser File, Close, then wait about a minute before Poser File, Exit, the issue mostly goes away.

My suspicion is that 'just closing' preempts 'trash collection'...

Now off to ask where the old facility for reflectivity mapping went...