And on cue, all the classical guitar majors give
the look of incredulity.
And they are very talented! 😊
But what I mean is, we can only actuate one string for a given note at a time. Meaning you cannot play two notes on the same string at the same time.
If you push your E2 string down at the third fret...you cannot also push it down at the 7th fret and play a note for both frets. Only one can be actuated, and it will be the one furthest down on the string.
Having two identical fretboards, can allow you to play two notes on the E2 string at the same time. Because there are now two E2 strings and you are able to play with two hands simultaneously.
Naturally, you can use chords to get around this limitation...but two fretboards and two hands still allows twice as many chords at the same time, as well. So my statement is still true...