QV links tables during the load together with same fieldnames (case sensitive). If you have two source-tables with three matching fieldnames it will generate a so called sync-table including these fields.
This is a very comfortable and fast way to build a QV-datamodell, but you have to understand the details. If you do not want to link tables together you can rename the corresponding fields using the keyword "AS" in your load-statement. This is similar to SQL-Syntax. For more see Online-Help and.or your Manuals.
HtH for the first steps