"PaulaJay1"
I guess with two chips, I can update one
early and keep in the plane and change on time and then bring the old one
home
for reprograming next month

Two memory chips is a good idea anyway. I had a chip on my Garmin 300XL go
bad. It programmed successfully but the unit wouldn't read it. Fortunately
I had 2 and simply used the old one for the VFR flight (yep, out of date).
Now I always have a backup, backdated or pre-dated chip with me at all
times.