HKCU\Software\Kerio\Synchonization Plug-in\<Outlook profile name>\DumpXml to 1 (DWORD)
this option will create XML files with SyncML communication between KSP and KMS (requests and responses). This is useful for solving problem with duplication of contact and calendar items. The files are located in C:\Program Files\Kerio\Synchronization Plug-in\Send<number>.xml and Recv<number>.xml.