I would strongly recommend removing the glue. It can usually be removed easily with a 4" or larger razor scraper, like the ones used for removing wallpaper. Then follow up with an acid wash or whatever the manufacturer recommends.
Another concern is that, being in a basement, you may have a problem with hydrostatic pressure eventually causing the epoxy's adhesion to the concrete to fail. It might her a good idea to test for slab moisture by taping down a 2'x2' piece of plastic for 48 hours. If it is dry underneath when you remove it, you should be good .
You may well have success without thorough prep. When I'm hired to do things like that, I can't afford to have a failure. Because of that I have to assume the worst.
Two things that may happen are poor adhesion and the telegraphing of any bumps or ridges from the existing adhesive.
kurplop, why u no respond to PM...Show Image(http://emoticoner.com/files/emoticons/onion-head/dying-onion-head-emoticon.gif?1292862500)
kurplop, why u no respond to PM...Show Image(http://emoticoner.com/files/emoticons/onion-head/dying-onion-head-emoticon.gif?1292862500)
Just got back online. PM answered.