Non-overlapping bars when using some series on secondary axis

A quick solution could be:
1. Add 4 empty (zeroes) series (move them in between real series in series sequence)
2. Format last 4 series (2 empty and 2 freq) to be presented on secondary axis
3. Delete dummy series legend entries - click on legend to select it, and then click on series name (not on a color square) and hit Delete on keyboard

See step by step instr. in attachement