Europe's map on a Garmin device is divided to All North and All South part.
D6210070A.img is All South map, so do NOT delete it.

From your screenshots the upper 2019.20 map on your device list is All North and the lower is All South.
Those are not two "versions" of the map but two parts of the full Europe map, complementary to each other.
Those two maps also appear on the pull down list "Currently Dispalyed Map" plus a third one, the one installed on your computer. This map is the full Europe map and you must always plan your trips on this map when using Basecamp.
So you don't have 5 maps but 2 partial maps of Europe on your device list on the left and again those 2 partial maps plus the full map of Europe (installed on your Mac) on the list on the right. The problem is that Basecamp doesn't show All South or All North or All Europe in the map's name.
If you planned a trip on Basecamp using the the full Europe map installed on your Mac and this trip is using both partial maps on your device, you must have both of them active (checked) on your device before you connect your device to your Mac, so the route is correctly calculated when your device will start. On my nuvi, when only 1 Europe partial map is selected, the calculation of such a route never ends. On your Zumo maybe it is finally calculated but with straight lines.
Another common problem that depends on each device "route" memory is how long is your trip. If your trip for example is longer than 1500 km then maybe you'll get a straight line near the destination of your route, because your device has not enough memory to calculate the last part in detail. As soon as you start driving along this route and you come closer to the straight line part, it is going to be calculated in detail because some "route" memory is now available.