There are a lot of different vinyl grain patterns out there. If you have ever looked through the legendary catalog, you can see that Mopar used a dozen different styles themselves.
I'd venture a guess to say your covers are professionally made by an upholstery shop and are not original factory covers. They likely found a grain pattern as close as possible to the original, presented that to the buyer, and made them up that way. This could have been a less expensive alternative to using Legendary covers, could have been the buyer didn't know exact reproductions were available, could have been a barter for other work, the situation could have any of a number of differing scenarios.
The use of the original green material is not suprising as upholstery shops need additional material in blind spots on the covers to create reinforcements, bridge gaps, and provide wear resistance. Often this material is the same, or similar to what being used, but it can just as easily be whatever scraps of stuff is lying around. I once had an interior with the same situation, only the extra material was some beige paisely curtain material. The rest of the bucket looked very similar to factory and if it was not for the cloth inserts, would have passed as factory to the casual observer, but closer inspection revealed them to be aftermarket all the way. A conversation with a previous owner confirmed this for me that he had them redone to be as close to original as possible, but with a slight twist, ie the cloth inserts.