using a command button to add a record to a table

[Guest_imported]

Hi.
I have two tables: one of referrals and one of actual patients. They are both in the same database. I would like the user who inputs information into the referal form to hit a command button that automatically adds the record that they are viewing into the patients table. I understand how to use an append query but I am confused about how to only add one record at a time without creating duplicates in the patients table.
thanks lots.

 

[Kjonnnn]

Would that mean there would be the exact sample patient info in two different tables?

 

[Guest_imported]

yes. all of the information from referrals will be included in patients table. But the patients table will have additional fields