A Minor 7th chord is a minor triad containing only a root, its minor third and its perfect fifth (I, iii, V) with the addition of a minor seventh (vii) as shown in the schematic above.
There can be multiple versions of each of these notes by fretting the same note
on different strings. Sometimes the same note is repeated, other times the note
is duplicated one octave higher.
In each case, though, the character of the chord is preserved.