I would be happy to try and assist with the duplicate number issue. Though I believe I am going to need more information on the desired result, could you possibly attach a sample packaged workbook that demonstrates what has been attempted?
For more information on how to packaged a Tableau Desktop workbook, please see: Packaged Workbooks
Formatting of the spreadsheet created in the export process is currently not built into the Tableau Desktop or Tableau Server product. To show support for the feature request, add you vote to the following Tableau Community Idea: https://community.tableau.com/ideas/1398