[EDITED] In the add-on's options (gear button), if you are using "Entire row is a real link" at the end of the first group, try turning it off. It seems to double-open if that is enabled.

[UPDATE] In version 1.4, I fixed the double-opening problem with that setting, but I can't get the page to open in the same tab in Firefox 94, only in a new tab. Hope to figure that out later.

[Nov. 12, 2021]

> One final Q - the list is not sorted based on the most FREQUENT on top. Is there a way to sort it?

I am showing the sites in the order Firefox gives me, and I don't have enough information to re-sort it. (I get title, url, and icon as described on this page: https://developer.mozilla.org/docs/Mozilla/Add-ons/WebExtensions/API/topSites/MostVisitedURL )