Unless anyone thinks that the boost from the true power of both Rinnegan (Just see One Eyed JJ Madara to Dual Rinnegan JJ Madara, and please don't use Obito and Nagato as references) , and a piece of Hagoromo's chakra itself is that much weaker than the piece of chakra Kakashi salvaged from Obito, RG Madara wins.
1. Getting both Rinnegans increases chakra
potency (meaning it strengthens whatever chakra one already has.) Determining the boost Madara gets from both Rinnegans based of JJ Madara before and after he gets his second Rinnegan wouldn't be an accurate comparison. If I used numbers:
Madara's chakra pre-Jinchuuriki=100
Madara's chakra after becoming JJ=200
Let's say being an original wielder of the Rinnegan strengthens chakra by a 2x boost. 100x2=200, but 200x2=400. See why the difference between JJ Madara w/ 1 eye vs JJ Madara w/ both eyes >>> the difference between SM Madara w/ 1 eye vs SM Madara w/ both eyes?
2. Then there's the fact that Madara received two power-ups in between the versions of him you are talking about (attaining a second Rinnegan as well as absorbing the Shinju) so you can't attribute his increase in power only to Rinnegan.
3. And how specifically are you comparing JJ Madara before and after he gets his second Rinnegan? If it's based off the scale of his CT, that wouldn't be an accurate comparison considering we have no idea how strong his CT would be before getting the second Rinnegan (ignoring the fact that he can't actually perform the jutsu with one eye.) You can't base it off his usage of Limbo before and after getting the second Rinnegan, that's only a 4x boost because Madara could make 1 Limbo with 1 Rinnegan+SM, but make 4 Limbos after getting Juubi's chakra+absorbing Shinju+second Rinnegan.
4. How can you definitively prove that DMS Kakashi's Susanoo would tank Shinsuusenju+12 giant BDs with Susanoo blades?