You can run TLC plates with more solvents and compare the Rfs. An alternative that works well is to spot the two compounds together on the corner of a square TLC plate. Run the TLC plate in one solvent (e.g. the one in the question) so that the spot is about 2/3 of the way along the plate. Now turn the plate thro' 90 degrees and re-run the plate with a different solvent in the new direction. If you still have one spot then they are likely to be the same material.
When running separate plates you could also use spray reagents and UV to visualise the spots. Different materials often have slightly different colours/reactions to the visualisation methods.