According to Capeller(sp?), the nominative dual form
from kRSNa (kRSNau: two Krishnas) refers to Krishna
and Arjuna.
Capeller's Sanskrit-English Dictionary:
1 kRSNa a. black, dark. --m. (ñ{pakSa}) the dark half month, the black
antelope (mostly {kR3SNa}); N. of an ancient hero and teacher, later
as the god Kr2s2n2a identified with Vis2n2u; du. *****{kRSNau} =
Kr2s2n2a and Arjuna.***** f. {kRSNA} a. black kind of leech. N. of
sev. plants, E. of Durga1 and Draupadi1; f. {kRSNI3} night. n.
blackness, darkness.
