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If it is not the case then you do risk being banned. Happened to me (I think). Anyhow one of two URLs disappeared from the index and it was the one I wanted.
When I put the 301 on the other one, back to the one that had been dropped ( and also wrote to google to explain ) I was returned to the index under my preferred URL.
Lots of info in other threads here on how to effect 301s and what they are...