Use one .typ file per mapset. Let's say the one you have already installed is named topo.typ. Make two copies of this file and name one of them oregon.typ and the other one 60csx.typ
Now modify oregon.typ with whatever colors, line widths, patterns, text styles, etc that you prefer for that gps. Then modify 60csx.typ to whatever styles you prefer for that gps. After you have each the way you like, duplicate oregon.typ and change the name of the file to topo.typ, then drop it into the mapset to replace the original topo.typ. You can then send the map to your Oregon and you will be all set.
Now duplicate 60csx.typ and change the name to topo.typ. Swap this file with the one in the mapset. Send the map to your 60csx and you're all set.
Just keep copies of oregon.typ and 60csx.typ separately for future use, and you can continue to modify them as desired to tweak the appearance on each gps.