Hi catymag. I am sorry it took so long to reply. I lost my internet connection. It wasn't restored until a few days ago.
Yes, I do have another map covering mostly the same (but not 100% identical) region. It is the original 2011 map that came with the unit in the .system hidden folder. The newer unlocked (2012) map I placed in a folder "map" in the root directory of either the GPS itself or the SD card.
I read some where that if you remove the original map on the 3790T, then voice command would stop working. I don't know if it is true. But I figure, since there is enough room to keep both maps, I would just leave it be, and uncheck the older map within Garmin under settings. Should I have deleted the original map from the .system folder?