The problem this finds
Mouse switches are tiny metal springs. As they wear, the contact starts to bounce, and the mouse firmware, which is supposed to ignore that bounce, lets one through. From your side: you click once, two clicks arrive. Files open when you meant to select them, drag and drop lets go halfway, and in games your single shot becomes two. It shows up after a year or two of heavy use, sooner on mice that have been drag clicked.
How to read the list
Every click is timed against the previous click on the same button. A person clicking on purpose can't get two clicks closer than about 80 ms, and a relaxed one-per-second click is nowhere near it. So any gap under 80 ms is flagged in red as a double fire. One flag in fifty clicks could be a slip. Ten in fifty is a switch that's going.
Test each button separately: the left switch usually dies first because it does the most work, but middle and right are checked the same way.
What to do about it
- Some mouse software has a debounce or "click latency" setting. Raising it a few milliseconds hides the problem for a while.
- Compressed air into the button gap occasionally helps if it's dirt rather than wear.
- The proper fix is a new switch. On many mice it's a small soldering job; on a few it's a socketed swap with no soldering.
- If you're testing a new mouse and it double fires out of the box, that's a return.