iCal/Google adds multiple alerts with random times

I have a google calendar synced with iCal on my Macbook and 3 iPhones. Most of the events on the Google calendar have reminders set. Frequently, multiple reminders (as many as 5) will suddenly appear on some or all of the events. The times of the reminders are odd, 13 hrs and 9 min, 2 hrs 5min, and are in no way related to the time of the event or the original set reminder. I have checked the Google account, the computer and all the phones and none have default alerts set and the time is set to our local time.

What could it be? I am so sick of having the reminders go off at odd times of the day then having to go in and manually remove the unwanted reminders.