OK, I have a lot of experience recording classical guitar, both solo and duo.
I'm going to potentially throw a spanner in here - I definitely wouldn't use ribbon mics unless the players have some serious projection and your preamps are whisper quiet. I have simply found ribbons (Royers) to be too noisy for this.
You will only need 2 mics - forget room mics or spot miking, you need to approach this from the viewpoint of classical recording techniques. IMO the best mic array for 2 classical guitars is MS using excellent SD condenser mics (I use a Schoeps MS pair), which will give you fantastic stereo imaging and pick up the lovely acoustic of the church you will be in.
Alternatively I have had lots of success with ORTF or AB omnis spaced at about 40cm. The key is getting the mic placement right, so spend plenty of time with this - usually about 1-1.5m back from the instruments pointing a little above the level of the soundholes .
If you stick with these tried and tested stereo methods you will NOT NEED PAN, just go straight in on a stereo channel. The intention is to reproduce the performance, so placement of mics and players is more important. Forget compression - I assume you'll be recording at 24 bit, so this will give you all the headroom you need, I usually let my peaks settle at around -8 dBFS.
Good luck!
