Since I couldn't get a direct answer, I downloaded and installed chirp. I am assuming you used Chirp's default FRS/GMRS lineup. If that is the case, you should have FRS 1-14, and GMRS 1-8 All channels are simplex. GMRS 1-8 are actually channels 15-22 on the bubble pack radios. If both radios have the same FRS/GMRS chart installed then they should both work if they are on the same channel.
Now, you keep talking about GMRS channels 9 and 10 which is NOT in the factory chirp file which surely you now understand my confusion and why I asked about how you have programed the radio. GMRS 9 and 10 could be FRS 9 and 10, they could be repeater channels, they could be a goofed up channel you put in. Without seeing data and instead being given info on power output means I cant help you figure out where the mistake is. It could be a programming error, a bad code plug, could be one of the radios was defective, could be human error. Without the info I asked about I cant even begin to figure out what is going on.