Thumbnail images

For several reasons sometimes I regenerate thumbs. At this point my original gets a say 110×160. Then later it would make say 109×160. So I delete the orphaned 110×160. I thought it was due to the new WP ver. But no, later it makes a 110×160.

I have 1000s of orphan images due to these 1px diff files. Haven’t found a plugin that could clean them. Haven’t found why WP can’t make up its mind.