Much like what was happening in Bug 1471873, when you have "Recent Applications" turned on running 10.14, you will see multiple instances of Nightly in the Recent Apps tray. STR: 1. Confirm in Settings | Dock that Show Recent Applications is checked. 2. Using latest nightly open Browser Toolbox from Tools menu several times 3. Observe attached screenshot This doesn't appear to be an issue in 64 beta since I don't see that specific choice in the dropdown.

Thanks for filing Marcia. I think it might be because when you open the Browser Toolbox, a new instance of Firefox with a different profile is started. It's a bit odd that it would keep on adding more and more items in the Recent Apps menu every time you use it though. I would expect it to be there only once. (In reply to Marcia Knous [:marcia - needinfo? me] from comment #0) > This doesn't appear to be an issue in 64 beta since I don't see that > specific choice in the dropdown. If the dropdown choice you're referring to here is the Browser Toolbox, then it's never shown by default. It requires a couple of settings to be turned on first (https://developer.mozilla.org/en-US/docs/Tools/Browser_Toolbox). Marking as P3 as this isn't something that the general user population will encounter.