Firefox Dev Edition as Default Browser

Question

I manually installed Firefox Developer Edition, added it to the dock, and set it as my default browser. All was good, but now it displays a secondary gear icon in the dock when I open it by clicking a link elsewhere in the OS:

My default browser choice in settings also shows the gear icon. What's going on?

Edit with two details to add:

1. No matter which way Firefox Dev launches, it keeps its state (remembering open tabs, etc.). So if it launches via an external click of a URL, then I quit and reopen using the dock icon, it still has that tab open.
2. If I already have Firefox Dev open via the dock or Applications launcher and then I click a link in another program, it opens a new tab in the open Firefox Dev instance and does not add that other icon to the dock.

Answer 1

I found the same issue when setting Firefox Developer Edition as my default browser. Then when opening the default browser using a shortcut, it opens a separate dock icon.

I looked in ~/.local/share/applications and found the added shortcut. It looks like it was using firefox-bin as the executable.

If you change the executable in your custom shortcut to point to firefox-bin it should fix the issue. (it did for me)