I have found the same thing. Two commands get sent.

I also did not like the fact that without a ramp and repeat, you can't send the same button command rapidly one after the other. For instance, you might want to hit the skip forward button 4 times in a row to skip a 2min commercial break. But using the RS-232/USB interface, you can't send those commands rapidly. Only 1 or 2 of the 4 presses get noticed.

So I ended up putting an IR emiiter on the HR20, and using the IR emitter for up/down/left/right/ch+/ch-/skip forward/skip back. I use RS-232/USB for the other commands.

If anyone knows of a way to do this properly via RS-232, I'm all ears.