This is because you are reading the same sheet twice
You have to set the sheet variable to the sheet name. As it stands, you are sending the file variable to read the file, so you end up reading the file twice and reading the same sheet.
So, the first thing to do in your Excel Reader is to choose the option “Select sheet with name”:
Then go to the Flow Variables tab, and assign your variable to the sheet_name variable:
One additional information. If your sheets have different columns, the Excel Reader might complain. In this case, use the “Support changing file schemas” in the “Advanced Settings” tab:
EDIT: Also, please avoid using deprecated nodes. Deprecated nodes mean that they have newer versions that should be better or have new features, which you can take advantage of. Also, deprecated nodes are removed in newer versions of Knime