I'm looking at the Nauticam dual flip adapters and there are two options with large price differences.

 

First is the Nauticam M67 Double flip diopter holder for 67mm Macro Ports for $503. This seems pretty straight forward, there are two 67mm threaded adapters.

Next is the Nauticam Flip Holder Double, M67 for MWL-1 for $387. This appears to come with an adapter for the MWL-1 lens. 

The price difference percentage wise is quite large for what appears to be a similar product from the same manufacturer. My question is mostly regarding the MWL-1 model, is the MWL-1 adapter exclusive to the MWL-1 lens or can the adapter be removed and expose a second threaded 67mm adapter? The idea being that I can pay $387 and get the same thing as the $503 model. Is there an opportunity to save money? 

I use the first one. It's very well made and works exactly as expected. I use it on a Nauticam housing with the KRL-09 and SubSea diopters.