No idea how to even search for this so it may have been reported already, and it's not important anyway but it is a bug. Or at least a quirk.
I lost a fortress to Vanheim in a game I was playing, writing was completely on the wall so I quit, deleted that game. Started a new game with same settings and opponents and named it the same as the original game so as to keep my testing straight.
the start province I got was the same province I had lost the fortress in Last game. There was the combat icon in the province and I could watch that fight from the Last game. It had no other effect on the province, same normal starting troops gold etc, so it's a bug that has no effect that I can tell but I figured I'd report it just for the heck of it
Who knows how these things work, maybe it'll have some significance in solving some real bug later.