Do you not have a github for your addons? Writing here is not that comfortable.

Anyway: The "dupe" menu should have a right-click menu entry to remove all dupes (except one tab of course).
In addition, the list needs to be locked after clicking the x button to close a tab and unlocked after sorting the list again. Right now there is no fast way to close many dupes, because just clicking on the last entry multiple times without waiting for the list to update will remove all tabs, even the last one, because the click gets registered before the tab should have vanished from the list because it was the last one.