I have a complex 2003 formatted *.xls file that some users are running in
Office 2007 and 2003. This seemed to be working fine until the 2003 users
couldn't open the file due to "Too many different cell formats" and the 2007
users witnessed formatting disappearing. I have identified that the workbook
now had about 3000 different styles. I have worked to reduce this number
(painstakingly I must say) and it works fine for both users. I want to
prevent this issue from occurring again. Why would all styles keep
duplicating themselves (like Title 1, Title 2, Title 3, etc) and how can I
make it stop?

Thank you for your help.