When the Atreides arrive on Arrakis, there are a number of instance where the Fremen call Paul Mahdi. While I realise that Mahdi is Arabic for guided one, I can't help but wonder at its close homophony with Muad'Dib. Could the Bene Gesserit have misinterpreted the prophecy which mentioned the "coming of Muad'Dib" to mean the more logical, "coming of Mahdi"? Was this misinterpretation subsequently implanted on Arrakis by the Missionaria Protectiva? Or perhaps, did the Fremen, over time, reinterpret Muad'Dib to actually mean Mahdi?
In other words, is the Fremen Mahdi an eggcorn of Muad'Dib?
(The converse where Paul could have misremembered the Mahdi from his dreams as Muad'Dib seems a little more (if that is at all possible) far-fetched.)
P.S. Does Mahdi find mention at all in the series after the first few chapters of Dune?