Yeah, I got duplicates as well. You may want to use more titles for entries (e.g. vacation, home, work) to avoid massive work of deleting the duplicates from one calendar. Also, the good way to avoid the duplicates is to use "From Google"-sync only. This way you can't get duplicates. If you let your calendar add entries to the Google Calendar and vice versa you might get duplicates, again. So in short : use more than one title for entries and sync from Google. One way sync should be fine, two way sync seems to be troublesome, for now (or maybe it's just PEBKAC).