Is it normal for the 2008 Honda CBR600RR to light up only one headlight when the headlight dimmer switch is NOT in high beam?

, and both headlights light up when the

headlight dimmer switch is on high

Yup

Yes

Yes.
All sportbikes work that way.

Ya think?

That is exactly what it is supposed to do.

Take the bulb that isn't working out and check to see if the low beam element is broken jojo.

As goofy as it looks - yes.

Maybe. Some countries have them set up like that. The bulb in one lamp is just a high beam.
Other markets have normal hi/lo bulbs fitted to both lights. Ring your local Honda dealer and chat.

Yeah it's normal don't worry about dude see below