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It's considered polite to use the big textbox to ask a comprehensible
question, not just use the subject line.
As noted elsethread, this is probably a Bad Idea - relational databases use
the Grandmother's Pantry Principle, "a place - ONE place! - for everything,
everything in its place". Storing the same data in multiple tables risks
anomalies if one or the other table gets edited; you then have "the same" data
actually being different.
That said, an appropriate Query (append or update) could do this. If you would
like help with a query post some more information about your tables and what
you're trying to do.