Up until yesterday, when I opened Firefox, a window opened and the icon in Windows (10) had a line under it. Now a second icon is created with a line under it. If I click on the original icon, another window is opened. I've tried reinstalling the last version of Firefox with no luck. I removed the pinned icon, opened the program and repinned it, which immediately resulted in a second app icon in the task bar. Is there a setting in Firefox that changes this behavior? This only happens with FF (so far anyway).