Q: Which of these apps do you own?
Okay, you own SmartPad and purchased SmartDay for iPhone. Thanks! Your data will not be duplicated as long as you do not also sync SmartDay iPhone with your iPhone Calendar. If you do sync with your iPhone Calendar and to mySmartDay, your data will be duplicated because of a ‘sync loop’ with iCloud and iTunes. Just use the “Remove Suspected Duplicates” feature in Settings of SmartDay for iPhone to remove the duplicated items, then sync both with mySmartDay. You should be good to go!
To set up sync for the first time: In SmartDay for iPhone or SmartPad, just go to Settings and verify your free mySmartDay account. If you do not already have an account, you can create one from Settings -> Synchronization.