dchemphill1

While GMRS is a bring-your-own-contacts service you can bump into strangers.  It's not like amateur radio but it can still be amusing.  I'm new to this and when I first connected to a local repeater my radio check was picked up right away by a trucker who uses HAM, GMRS and CB. He was legit in his usage but also ID'd with his handle; “This is XXXX123, a.k.a. 'Roadrunner,'” or something similar.
Since my HT was fresh out of the box the roger beep was on and he gave me the Sad Ham treatment about it.  “I'm gonna call you Mr. Roger Beep.”  I replied, “Yeah, I've heard that some people don't like the roger beep.”  He came back, “Hey, I've seen that 'Some People' guy.  He's good!”
Roadrunner: Hey, Mr. Roger Beep.  You out there?
Me: WRYP592, a.k.a. Mr. Roger Beep monitoring.  Rested and ready to beep.
And we're off...

Channel 17 and channel 17rp both receive on the same frequency.  That's why you hear the same chatter on both channels. But the channels marked rp differ in their transmit frequencies.  They are for specifically configured for repeater use.
A radio set to channel 17 receives and transmits on the same frequency, 462.600 MHz.  That's referred to as a "simplex channel."
A radio set to channel 17rp receives on 462.600 MHz, but transmits on 467.600 MHz. That's the 5 MHz offset Randy (@OffroaderX) mentioned.
The repeater receives on 467.600 MHz and is designed to simultaneously transmit what it receives on 462.600 MHz.  Transmitting and receiving at exactly the same time is called duplex.