Where does it say Hagaromos chakara is only in the rinnegans? Madara used Hashiramas dna in order to get Ashuras chakara. Notice how in the panel it says he mixed his own chakra(indras) with Ashuras and THEN brought out my(the sages) chakra and that's how he awakened the rinnegan. He explains it in sequence. Madara mixes indra's chakara and ashuras chakara together and gets the sages chakara THEN he gets the rinnegan. Meaning he already had the sages chakra in his body before obtaining the rinnegan. And that was for DECADES. So no I seriously doubt the sages chakra comes from the rinnegan it self.... He needs the sages chakra to awaken it... Here's the same scan from above.
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If you can find a scan that says otherwise I'd like to see it.