Kubuntu creates a backup file every time i append a file and save it at the time of closing Kate editor. I am using Kubuntu 11.10
It seems you forgot to ask the question :) I'll assume the question is "how do I disable creation of backup files in Kate"
The answer is: go to Settings - Configure Kate - Editor Component - Open/Save - Advanced and untick "Backup on Save" for Local Files and Remote Files. Then click OK.