This is actually a common misconception and I made a lenghty thread explaining how this is wrong and detailing how the Cursed Marks actually work. THere is also a very huge problem with the idea of the multiple orochimaru idea which is this.
If the orochimaru that was inside of Anko is a seperate entity from the one inside of sasuke or the REAL oro then how did it know, after it was pulled out of anko by sasuke, how to undo the RDS? It was locked into Anko the entire time and thus would not have known anything about that since it never had its arms taking from it, the real oro did but it is separate from it. Infact that would mean that it would still have its oroginal arms since it is separate from the real oro.
I go further into this in my thread, i recommend you read it
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