As far as I know, it's not correctable. It's simply information that's useful in certain situations. It's possible the record got moved for some reason and sent back.
Question: are you showing the members their membership record or the IOS? Handbook 1: 13:6 says you should never show the membership record to the member. But you are free to print the IOS and hand that to them. There are only a few differences. The "Prior ward" field may be one of them.
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