Yes, clicking the FF icon causes a new (another) instance of FF, but the new instance substitutes itself into the tabular position of the original instance of FF, and the original becomes unavailable/inaccessible, until the new instance is closed. There is only a single tab on the FF browser, where one would expect there to be as many tabs as there are instances of FF. No, a single tab, which shows the most recent instance of FF. Earlier instances are not accessible or visible again, until the last instance of FF is closed. Whereupon, the next-to-last instance shows on the single tab.