Ghasts in minecarts travelling in a loop duplicated, has not happened since first time, but it happened with 4 ghasts at the same time. 3 of the 4 ghasts did NOT retain their names, and despawned when leaving the area, but the fourth did keep its name and did not despawn. Ghasts could be hit, and minecarts could be broken and picked up.

edit has happened again. Again, no way to do it intentionally, but now there are 2 named ghasts and 1 extra empty minecart on one rail.