Why am I getting double popup alerts for Google Calendar events on iPhone?

This is happening on both mine and my wife's iPhones (mine is a 4 and hers is a 3GS) which are both on the latest iOS (6.0.1). This is what I've figured out:

On iPhones: Default is to set no alerts/reminder for calendar events

On Google Calendar: Default is to set a popup alert 1 hour before event & email 1 hour before event

When I create a new event on my iPhone: It saves with no alerts set, then after uploading to google calendar it shows as having two alerts 1 hour before the event. If I go into Google Calendar, it shows that 1 popup and 1 email are each set for 1 hour before the event.

When I create a new event on in Google Calendar: It saves with 1 popup and 1 email are each set for 1 hour before the event per the default settings. If I go to my iPhone, it shows that I have 2 alerts, both for 1 hour before the event.

So it seems that the iPhone is seeing both the popup and email alerts and creating two popup alerts on my phone!

Is there anyway to fix this? I've tried setting up the calendar on my iPhone through Gmail account, Exchange account and CalDav account and it's all the same.