Viewing Multiple Maps on Computer / De-Duplicate Map Data?

[greenfrog5]

I know MapSource cannot display multiple maps at once.  I don't think BaseCamp can either?  The GPSr can, is there any other way to see how a transparent map will overlay over other maps (like it does on the GPSr)?

I'm making trail-maps, but don't need to waste time on certain things when other maps (California-topo) already cover dirt roads and some trails I might hike and add to my map?

I have quickly traced things off of maps in MapSource, then viewed these Routes/Tracks over my in-progress map, but this doesn't save much time.

Thanks
Aaron

[Boyd]

This has been frequently discussed, and it's not possible. You might be able to do it with Garmin MobilePC, but that isn't free: https://buy.garmin.com/shop/shop.do?cID=165&pID=13484

Looks like this software has been discontinued - must have happened very recently. You can install and run it as a free trial for two weeks however, so you could give it a try. See this: http://forums.gpsreview.net/viewtopic.php?t=13951