All aviation databases (they do not call them maps) are stored directly onto unit's built in memory, not on SD cards. The map on the SD card is something which was in the unit when I bought it from previous owner a long time ago. It does not affect the databases in any way.
Using GMapTool I discovered the map is:
CN Europe NT 2012.20 ALL
PID 1
FID 2473
U: PJDUT-VWFGX-YLY2H-3RRS6-GJLQT
UNL: T4F8F8HKUMPBZLSD8W6GV5UJC

Thanks for any help.