I'm using a Message List - sorted by date, descending, unthreaded. So a simple layout. I have the 'Message Pane' enabled. when I select - single left click on one email in list. The contents are displayed in the 'Message Pane' below. However, if I hold down/press the 'Ctrl' key at same time then each time I do a left click, it is still selecting the original one and also the next one I clicked on. In the Message Pane' it now says : 2 conversations and shows a short bit of info on each selected email. These actions are called events and are very specific. If this was a problem with code then everyone would experience a problem. So this is unique to you and not a bug. Possible reasons: You may have developed a habit of unknowingly depressing the 'Ctrl' key as you select an email. You would not be the first, the 'Ctrl' keys are typically in the bottom right and left corners and I have come across people accidentally and unknowingly pressing them. They are leaning a bit on the edge of the keyboard. You have a 'Ctrl' key which has become sticky. You may have used it and it has not fully released. Maybe it needs a clean. But this type of issue is known to occur in other situations. Make sure your drivers are up to date. The info at this link mayprove useful to unstick/reset a stuck key. https://superuser.com/questions/956049/control-key-acts-as-if-it-is-stuck-periodically

This is also a helpful link on Ctrl key sticking topic: https://toolspond.com/ctrl-key-is-stuck/