Same way- they will still register a collision. You may want to make both platform objects jump if they are moveable objects.
But objects with platform behaviour can jump only on solid floors isn't it? Anyway sprites with platform behaviour doesn't jump of each other...
You can if they have the solid behavior but how are you using more than one platformer object in your game?
If you have more than one platformer they will all respond to movement controls?
Your questions asked how to bounce solids. Solids are not a platformer with movement behaviors but platformers can also be solids.
So I would have to see your capx to see what you are doing?