Using the Distinct Option:
Note: When running a query, occasionally the same row of output may be listed more than once when it meets multiple query requirements. Using the Distinct option removes duplicate rows of data. However, the end-user should note that this option may remove pertinent duplicate information, depending on the query. Therefore, if the end-user is not sure if any pertinent data will be removed by selecting this option, the safer alternative would be to run the query results to Excel and manipulate the data in the spreadsheet.
If the end-user is confident that pertinent data will not be removed, the Distinct option is located in the Query Properties box.
Click the Properties link.