Re: Was the U.S.S. Horatio an Ambassador Variant?
Two Ambassadors are possible, although could be confusing during battle maneuvers and there is probably some attempt at avoiding such overlaps by Starfleet Operations unless in situations of dire need (like a Borg attack, neutral zone incursion, etc). Two Ambassador classes co-existing at the same time, however, not as likely.
I may appear unoccupied to you, but at the molecular level, I'm really quite busy.