Although it's not supported by Mark, you can open the ADX as a TXT file, highlight the dashboard that you want toove to the new ADX, copy, and then paste into the new ADX, save.

You're not done yet though, you then need to open the ADX in TP RT V5, right click on the gauges that don't have proper assigned values, and incorrect values, selecting the proper items from the menu that comes up, save again, now you're good to go.