Is it Possible to Collide Two Mesh collider ?

Yes,It is Possible.

Two Mesh Collider can not have interaction unless at least one of the is Convex.

Convex, If you set this to True , Mesh Collider want have any holes or entrance.

- Convex Mesh can collide with other Convex Mesh collider and Non-Convex meshes Collider.

- Mesh Collider are Computational expensive.