I suggest you contact Riverpark and ask the specifically about using a copy of another unit’s SD card. It’s been reported a number of times on other RV forums that this is the not possible.
Here is word for word copy from your Owners Manual.
If you have purchased your navigation SD Card please do not misplace it. This card also contains a unique license and registration required to operate your navigation. You will need to purchase another license and SD card if you lose it.
When purchasing a new card from Riverpark they require that you provide them the serial number of your Xite system and they then add the software key for that system on the card they send you.
The infotainment system does not carry the Xite system and RAND navigation the SD card does. Nor does the radio carry your license, the SD card does.
You may not be aware, but Rand McNally has dropped RV navigation and has not updated Xite system maps and routing for 2-years. Xite has moved to NavNGo navigation and those of us with Xite systems cannot upgrade to the new system, we are expected to purchase entirely new equipment.
Many other RVs have used Xite systems over the years including both Newmar and Entegra.
A number of owners have replaced the Xite system in their RV. Your best bet may be to find a used System/Core unit, depending on the system you have.
Here is a very large thread on replacing the Xite system on irv2.com: