Does it have a chart? Or does it even show the GPS coords anywhere. And if it does show the GPS coordinates, what do you relate those to?
OK that all said... yeah, redundant handheld GPSs are no doubt the best current solution to the lack of charts issue.
And all that said, I happen to know of a group of sailors that recently completed the transpac and finished with no power, no spare batteries, and rationed the use of their only working handheld GPS on the last couple of days. So folks keep in mind that sometimes "stuff happens."