I have done single rounds or dual 359 style. As long as the wiring is the correct gauge there shouldn't be any melting. Are you using the factory 8 pin deutsh plug?
I used the factory plug. And bought h4 pigtails from peterbilt to replace the cheap wiring that came with the headlights. If I run my high beams to long it will melt the plug or blow the bulb. If been thinking of changing to the double rounds.