New in 3.7.0:

Added: Auto-close existing duplicate tabs on Firefox for Android. When you already have the same page open twice, the extra tab is closed on its own and the most recently used one is kept. It runs on startup by default, with an optional setting to also check every few minutes, or you can turn it off. A new "Clean up duplicates now" button (available on all platforms) removes duplicates on demand.

Fixed: Stale duplicate tabs were not being closed on Firefox for Android once a tab had been unloaded from memory. Android unloads background tabs and hides their address from add-ons, so a duplicate stayed invisible until you reopened and reloaded it. The extension now remembers each tab's last address, so unloaded duplicates are still detected, and it tidies up a stale tab as soon as you reopen it, with no manual reload needed.