The duplicate feature is on the to-do list for the HTML5. In the meantime, you can revert back to the Flash version, perform the duplication effort, and then return to HTML5.
To toggle back to Flash version:
1) Go to VisualRF -> Setup tab
2) Toggle Enable HTML5-based UI = no
3) Save
4) Give it a minute
5) Navigate to building with the region to duplicate
6) Either duplicate floor (with copy regions checked) or click into the floor and copy the region to floors above only. If you need to copy regions to a floor below, you'll have to play with floor plan numbers to get it so that all floors are above the floor that has the region to copy.
7) Repeat steps 1-3 (toggling yes) to revert back to HTML5