To be in the same folder, they would need different names. Where are you seeing this? I know the registry can confuse, as Revo Uninstaller shows two copies of Thunderbird when there is only one. Only one copy is actually there.

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If you look in the folder with windows file explorer, you will see one copy. Also, compare the dates of the files there. Are they August or December? If you uninstall one, you install it all. I have had this myself. There should be one copy of thunderbird.exe. If you start it, click help>about to see the version #.

>"If you uninstall one, you install it all."

Fear both rational, and confirmed by you as justified. Thank you.

I learned the hard way. :) Wisdom was never one of my strong points.