I've been continuing to experiment with two tarot decks and have found each reading to be useful. The primary deck is what I would call node cards. They represent specific people, events, issues, etc. The secondary deck is the connector cards and represent what connects the node cards to each as well as influences acting on the nodes. In cases where a connector card only connects to one node, it indicates either there isn't enough information or that the person hasn't done enough to get information.
From an enchantment perspective, I think the dual deck has potential as well. I'd use the connectors as specific influences to make a desired outcome for a specific node come into reality, while also using all of the nodes to support the outcome that was being created through the dual deck reading. That's the next experiment I'll be working on.
I find that using two decks in synch with each other is an interesting exercise because of the information that can be derived from using two sets of cards. It's an interesting approach to making meaning of the reading, because both sets of cards need to have some relevance to each other, but a lot of that relevance is derived from the reader or other people involved. What makes a connector have the influence it has, and why is that particular outcome shown? It's a system I recommend experimenting with for the sake of seeing what it'll show you. then compare to a reading done with just one deck and see if there's a difference. I've noticed more information with a dual deck reading than just a one deck reading, but your results may vary.