I've been reading into wormholes lately and understand how a wormhole with one mouth moving with a relativistic speed relative to the other mouth would constitute a time machine if the two mouths were brought close enough together. Apparently a physicist called "Matt Visser" calculated that it's probably impossible to bring the mouths close enough together and even if you do succeed the wormhole would become impassable. This supports Hawking's CPC and saves the universe from time travel paradoxes as long as you only have one wormhole. What I don't understand is why Visser doesn't mention using a second wormhole to make the journey back very quickly and thus travel back in time. What happens to Visser's conclusions when you add a second wormhole to make the return trip? Would using a second wormhole require additional physical phenomena to not result in time travel or have I overlooked something?