If that's the case, add a physic behavious to both of the players and enable "Prevent rotation" in their properties
I didn't totally understood the situation too but I don't think your answer will help him : if this guys adds a physic behavior on the characters, they will pass through the ground and every other platform because Physic engine and Platform behavior are not compatible. So your solution will certainly just create some problems (I suppose).
Now, author, as said by Oxy, we need to have more precisions. So, you have two sprites with platform behaviors. This behavior allow them to move around and collides with all the sprites which have a solid behavior
. So, why do you add a solid behavior to the playable sprites themself ? They don't need it to move and collide
. If your character can't jump when another character is above him, it's because this famous character above has a solid behavior
(so it's like a platform, so yup, you can't pass through it with your player).