I think you may be saying that Cantrell-1111 is the same person as a profile in your Gedcom, but for some reason they aren't matched in Gedcompare. If I have guessed correctly, you can go to your main Gedcompare screen, find the person who corresponds to Cantrell-1111, and click "COMPARE WITH" on the line for that person. That will give you a place to request a comparison with Cantrell-1111. When you compare them, you can mark them as a match.
I hope that helps.