From: United States
OSX Catalina (10.15.6)
Google Chrome (Version 86.0.4240.111)
Pinning rows doesn't always indicate potential duplicate lines.
I've uploaded a very simplistic game and pinned a row with a single 'X' in the right-most column. When you oust-over the other lines, only a single line turns green, when in fact 6 of the lines are potential matches.