I am trying to combine 5 separate tables using Access into a workable customer account list. I need to determine what overlaps of customers there are in the different spreadsheets. Eventually, I will have to combine all 5 of them into a workable Access database.

My first step is to compare the tables and find the duplications of customers. I used the Append Query on two tables from the same source. Instead of getting 650 records, I got over 12,000. How do I handle the duplications and why did my Append Query go wrong?