How to Play Pedal Tones with Two Guitars
Although a single guitar can play a pedal and a chord at the same time, in many cases, one instrument plays the pedal tone while other instruments play the standard chords. For example, one guitar may hold or repeat notes on upper strings, while another guitar plays through chord changes on the lower strings.
You can see this at Pedal Tone from Two Guitars.
You hear a pedal like this during the chorus to All the Small Things by Blink 182. One guitar plays the chords C5-G5-F5 while another pedals on C octaves in an upper register. All together the harmony you hear is C5-Gsus4-F5.
Here is an example of a two-guitar, double pedal tone. Here, the second guitar pedals on two different pitches over a I-V-vi-IV chord progression in D. The two pitches, D and A, are the root and 5th of the tonic chord, D. The combined harmony of the two guitars becomes more complex than the individual parts.
The first guitar may be playing only D5-A5-B5-G5, but the addition of the pedal tones by the second guitar creates the harmonies D5-Asus4-Bm7-Gsus2.