Multiple phones on same extension with EPM installed (FreePBX V12)

In an earlier setup, using Device/User mode, I was able to have multiple devices logged in as the same extension number, using the *11 to log in. This has been working perfectly well using the Aastra scripts, for about 2 years.

Thinking it was time to upgrade, I set up a server with Version 12, and bought the Commercial Endpoint Manager. I now find that trying to log in a phone to an extension number used by another phone results in that phone being logged off, and furthermore, it erases the configuration from that phone so it can’t log back in.

Is there an updated solution for this? The customer has a few “roving” employees who like to be able to have their extension at any phone in the company - 9 locations in 9 cities.