Banjo Dm7 chord (Double C)D minor seventh on the 5-string banjo: 2 2 0 3, and 6 more shapes

Frets, string 4 to string 1: 2 2 0 3 (open position)

1. String 4 (C): 2nd fret, index finger (barre), D
2. String 3 (G): 2nd fret, index finger (barre), A
3. String 2 (C): open, C
4. String 1 (D): 3rd fret, middle finger, F
5. String 5, the short g: open, G, not in the chord

Sounds: D A C F  ·  Dm7 is D, F, A, C (1 · ♭3 · 5 · ♭7)

The 5th string: the short g adds the 4th over Dm7, a colour rather than a clash.

Double C tuning: gCGCD, the short 5th string first, then strings 4 to 1.