CAUSE:Microsoft® Excel prints each worksheet as a separate print job; this is a limitation on Excel.

SOLUTION: To print the entire Microsoft® Excel workbook duplexed, follow this workaround:
1. In Microsoft® Excel select the first worksheet.
2.Select File.
3. Select Print.
4. Select Properties.
5. In the print driver select Duplex.
6. Select OK.
7. Select Cancel in the print dialog box.

Repeat steps 1-7 for each worksheet in the workbook.

8. Select File.
9. Select Print.
10. Select Entire Workbook.
11. Select OK.