I’ve taken some familiar two-word phrases whose words begin with the same pair of letters, deleted those letter pairs, then smushed what’s left into a single string of letters. For example, if I took the CH from CHINESE CHECKERS I'd end up with INESEECKERS.
To find the key to the final coordinates, turn each of the sets of letters below back into their original two-word phrase by adding a pair of letters at the beginning, then adding the same pair where a second word should begin. Put the letter pairs into the grid for your final clue:
You can validate your puzzle solution with certitude.