Yes Raze found a very good trick for this bug.
When one of your char is stuck, take the one who is not stuck as the leader.
Click on "Select all".
Move your character to the nearest stair (or door for a house, or cave entrance) and click on the stair.
The two characters will be teleport on the other side.
And you will be able to continue the game without loading an old savegame.
Have fun.
Barta