I’ve been running dual single filament headlights on my chop, lower is low beam, upper is high beam.

if not already,run at least hi beam off a relay with heavier gauge wire from battery to relay to lights,then the light switch will only carry the current required to trigger the relay,could also run lo beam the same way if you have enough room for relays ect hidden some where. current draw will be dependant on the globe wattage,could probabaly run LED globes too,if available to fit your lights.

You need to size the wire to the intended current draw, the fuse is in the circuit to stop the wire from overheating and causing short circuits.

I would seriously consider switching to LED lights instead of the duel filament incandescent.  Power drain will be a LOT less and hence far easier to manage. 

Thanks guys, lot of help there.. I think I may just wire it up hi on top low on bottom, charging and electrical systems on these were not great to start with! And the lights themselves suck any way! So two of them at once is likely useless!

That sounds like a good approach (Unless your riding in the country most city lighting is fine for 99% of the time so the bike may not need that much all up).