on conversion of an ODS file with charts to XLSX, additional data labels appear in Excel 2010 file only.
This does not happen when the converted file is opened in Office 2007. Reason being, after conversion, all the data label options are checked in the converted file when opened with office 2010.
The issue is handled in case of charts with no data labels in ODS files. But, if the input file has even a single data label option checked(chosen), the output file would contain all the data label options checked depending on the type of chart.