What are the advantages of using a duplex milling machine?

These machines can rough machine both sides, at the same time, of a blank to "near finish" or "finish size" on the thickness of a blank. This cuts the time spent finish machining on a more expensive CNC machining center to perform the more complex machining characteristics of the part. Unfortunately, this increases handling time, setup time, and adds another move and probably another storage point to the process.