Have you any idea how you managed to do that?

I would fully expect that if you delete or uninstall tb38.2 that tb38.3 will continue to work happily. What bothers me is that if you have somehow installed tb38.3 in a non standard location, it may not be overwritten when you subsequently update again, so you'll be back where you are now.

How do the two versions make themselves known? Do you have two separate start menu entries, or two separate desktop icons, or two quickstart buttons?

I think I'd uninstall both, then reinstall the required version afresh.

I presume that both installations "see" the same set of accounts, messages, settings? That is, they are both referencing the same profile? If not, you have done something quite out of the ordinary and some repair work on your profile may be called for.

Are either of these Thunderbirds of the "portable" variety?

I have the same problem. I've tried to uninstall 38.2.0 however the uninstaller prompts me to close TB which suggests that it will unintall more than the old version.

In my case there were two versions showing in W10 'add and remove programs'. I've solved this by uninstalling and reinstalling TB. All my emails and settings where preserved, I did however make a backup using Mozbackup just in case!

Zenos said

Have you any idea how you managed to do that? I would fully expect that if you delete or uninstall tb38.2 that tb38.3 will continue to work happily. What bothers me is that if you have somehow installed tb38.3 in a non standard location, it may not be overwritten when you subsequently update again, so you'll be back where you are now. How do the two versions make themselves known? Do you have two separate start menu entries, or two separate desktop icons, or two quickstart buttons? I think I'd uninstall both, then reinstall the required version afresh. I presume that both installations "see" the same set of accounts, messages, settings? That is, they are both referencing the same profile? If not, you have done something quite out of the ordinary and some repair work on your profile may be called for. Are either of these Thunderbirds of the "portable" variety?

I have a similar problem only my versions are 38.3.0 and 31.4.0. Both link to the same location but there is only one EXE program. I think there is a remnant in the registry. I also had 2 identical listings for Firefox but one went away by itself. P.S. This occurred after Windows 10 update.