Greg responds...

The two universes have some things in common. Some not. (Though this is all largely moot since Team Atlantis will never truly see the light of day.)

For example, they have their own Puck. (Though I suppose one might argue it's our Puck wearing a different body and using a different voice (Neil "Griff" Dickson's to be precise)).

They also have a different explanation for the Loch Ness Monster.

But they have certain things in common. And without a doubt the events that took place in Paris in 1920 took place in both universes.

Does that make it at all clearer?