I am attaching a dual screen effect that I use for presentations. The original idea is credited to Ben Balser for posting a dual screen template with reflection. I have modified it to include the ability to change the reflection, add blur, colorize the floor and background, reposition and rescale the drop zones and a few other items. I think you might find this useful. Feel free to further modify it as you see fit. I have labeled all the particular rigs so it should be easier to find adjustments in Motion if you need them.
To install, place the entire folder (after unzipping the file) in the Users/Motion Templates/Effects folder.
To use, drop it on a clip in the timeline and select the drop-zone in the plugin to add your screen shot or other video/image file.