Delegated Google Calendars duplicating on Apple Calendar

Since the middle of November, delegated Google Calendars (via my organizations Google Apps account) have been also showing up undering my main Google Calendar account in Apple Calendar 6.0. This is very troublesome, because I'm now receiving all the notifications for these other calendars. My Google Calendar account in Apple Calendar 6.0 (mountain lion) had been working perfectly before.

I've tried deleting the Google Calendar account and adding it back, but the issue keeps replicating. I also tried this workaround from the google calendar forum.

Any other ideas? Thanks for your help.

Jason