Kinda Random

I know this is kinda random but its something thats always bugged me. On almost all guitars there is the double inlay at the 12th fret to represent a one octave shift, but on some acoustic guitars there are two sets of double inlays, is there a reason for this or is it just astetics?

Inlays are usually just something that a luthier does to signify their instrument and give it a character. The double inlay helps the guitarist understand where they are on the fretboard. Harmonics exist at the 5, 7, and 12th fret, and these are where inlays usually exist.

You'd have to ask a luthier if there is an actual use for this, but i'm about 95% sure it is just aesthetics.

there just markers to help the player but become mute after you learn the fretboard(they have become pretty much standard but originally they varied form maker to maker) that and they have become silly aesthetics for people to look at. the harmonic thing is just a coincidence, that and 3/4,2/3, and 1/2 aren't really at fret because harmonics are going to follow just-temperament and there the only ones that fall so close to the frets because what about 11/12, 10/11, 9/10, 8/9, and 7/8 that all fall around the second fret.