The accolade listing at the end of the match doesn't show every accolade that each person won. You'll need to check your barracks to know for sure if you did or didn't get the accolade. It's located on the last page of the accolades in your barracks.
Beyond that I'd argue that while the objective is the same between the challenge and the op, it's much more difficult to achieve the accolade. You have to actually confirm more tags than anyone else in the lobby and that requires some skill. Maybe not as much skill if you are running a coordinated party but it does require some dominate play to beat out 11 other people running solo. I've gotten it several hundred times but I also play a lot of KC.