Chamois Rag Discoloured My Shoes

[Help!]

Hey folks! So I used a black chamois rag on dark brown shoes. Applied some RenoMat and noticed the leather had become darker. The black from the rag rubbed onto the leather. I tried in vain to reapply the Reno using a white cotton t-shirt. Rubbed and rubbed. Applied renovated and then polished. Nothing helped. This happened on a pair of Edward Green Ectons. Any idea on how to reverse the discolouration?! I’ve attached a picture to show the difference. I believe it’s obvious which is which :/
Thanks for any advice in advance!