AMS-SOU-AMS on ScotAirways in 2005..
DUS-SSA-USH-SSA-DUS on LTU (fuel stops in SSA).
Probably more likely, but nonetheless quite a niche route
LCY-DND-LCY
Again, I'm sure only few of us have done
PEK-FNJ-PEK
Also, has anyone done BAH-AUH-HKG on CX? It was the route they took for a few weeks when DXB had the refurbishment, I believe.