The problem is you have asked a very specific question, there probably aren't many people who have got the same generator, front and rear light as you.

Nearly any generator can be wired to any lights with a single wire and earth return.

By the same token nearly any system can be connected up using twin wires.

In the past all my generators have been designed as single wire, which I've ignored and run them as twin wire.

It's very likely that you could connect your lights to the generator with either a single wire or a twin wire, depending on what you want to do.

You could post some photos of the offending items if you like ?