Some users have reported an issue in which iPhones fail to sync with iTunes 9.2. In these cases, sync attempts result in the error message “The iPhone (name) cannot be synced. A duplicate file name was specified.” This problem may be accompanied by duplication of music and other media files.
There are two potential fixes for this issue:
Remove iToner. As noted in our previous report on iTunes 9.2 syncing problems, appears that the presence of Ambrosia Software’ iToner software may cause problems with syncing. Navigate to ~/Library/iTunes/iTunes Plug-insand/Library/iTunes/iTunes Plug-ins (the Library folders inside your user folder and at the root level of your startup drive) and look for a file called iTonerSupport.bundle. Remove it, then restart, and check to see if iPad syncing occurs more quickly.
UPDATE: Several users have now reported that updating to iToner 2.0.6 resolves this issue.
Turn off note syncing. In iTunes, navigate to the info tab and deselect the option to sync notes, then sync your iOS device. You may need to do this each time you sync.