alt+d in latest build

how do you do the new automatic seaming/mirror alt+d in the latest build?

It is odd, in 2.40a test build 2 you can only do “alt” + “d” in object mode. To mirroring is a lot easier in the new version. Just select part or all of the mesh in edit mode, go to editing in the buttons window “F9”, in modifiers press add modifiers and select mirror, and select an axis. Also the round button that appears next to the “^” button will display the vertices.