Create a workbook and add two sheets to it. Add a sheet titled 'test' Add a sheet titled 'Test'
Save the file and try to open it on Excel for Mac 2011 (14.6.4). Excel will complain that file needs to be repaired. The associated repair log is unhelpful:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <recoveryLog xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main"><logFileName>Repair Result to report (47) 03134.xml</logFileName><summary>Errors were detected in file 'Macintosh HD:Users:ccross:Downloads:report (47).xlsx'</summary><repairedRecords summary="Following is a list of repairs:"><repairedRecord>Repaired Records: Worksheet properties from /xl/workbook.xml (Workbook)</repairedRecord></repairedRecords></recoveryLog>
Seems like the issue is in the avoid_duplicate_name() routine which is case sensitive so it doesn't notice that titles are the same. Excel does notice however and this causes problems when opening the resultant file.
Perhaps this check should not be case sensitive?