This diagram is a simple representation of the parent scale concept with C Major. All of the modes that are derived from the C Major scale have first and last names that are unique in combination.

C Ionian
D Dorian
E Phrygian
.....and so forth

All God's children have names.

D Dorian has only the C Major scale as a parent. Same with E Phrygian and the other modal children of the C Major scale.

Modes for guitar