Can I split an electrical load across smaller wires for a bridged connection?
That would depend on the design of the appliance. If the appliance is designed to be wired that way - e.g., if each pair of L1/L2 is the connection for a 3,800 W heating element - then that should be OK, and possibly even desirable.

On the other hand, if the L1s are wired together (and the L2s wired together) - like the paired screws on a typical (not GFCI) duplex receptacle, then you can't do this because all current could flow on either wire - e.g., if one of the L1s came off of its screw then all the current would flow through the remaining wire, which would overheat.

Can't say more definitively without either instructions or schematics of the appliance.