Copy-paste (add) material

[creativemind]

Copy-paste (add) material, right now we can copy and paste (replace) current material.

I wanna be able to copy material and paste it on another part, making it a multi material. Saving the old material.

Bonus. If you can copy a new material that is not saved. And paste it into a multi material. Just with right click and paste or  shift right click in the multi material box.