The band system at 6300 is produced by atmospheric oxygen, therefore, is of telluric origin.
Because the resolution of 1.5 angstroms individual water lines are only visibly faded, especially as small shoulders in the H alpha line. The blends at 6500 are more intense water lines that overlap too. That is why they come so clearly. The lines from the object itself are split by Doppler effect (SB2 spectroscopic binary type). They are directly identifiable by splits of the same distance. In this spectrum we can see at a glance which lines belong to Mizar A (also the faint lines at 6250 and 6420). In this case the Doppler shift helps to identify lines of the object.