Two instances of the same browser app show as one on the Open URL action menu

[Ross]

I have two instances of Firefox, this shows fine in the applications list. But in the action menu for "Open URL" there is just one, I'd like to select which one it opens in. For reference I have attached a screenshot of the Apple preferences "Default web browser" menu which shows both.

I'm using Alfred 5.1.4

Edited February 23 by Ross