Mentor calls this "innovation" DATA CENTRIC LICENSING. I, along with many other user in the community, did not ask for this innovation...
With Expedition (or PADS professional) there is a workaround:
To make this a little bit easy on the layout people is to instruct them to open the second design from the tool as "open as reference" This will not consume additional licenses, but the design is in read only mode (sort of)
Hope this helps
I did discover the "open as reference" option, but being in read only mode one cannot export data (i.e.CES rules). You can copy (placement, routing) from the reference design back to your active design, which is at least one benefit, but it is still irksome that we had functionality removed, functionality which we paid for, but is now costing us 2X what we used to spend.
The same holds true for DxDesigner. we used to consume 1 license when opening one or two designs, now it always consumes 2 licenses when the 2nd design is opened.