Rich, what kind of phone was it? Did you try these steps for the double mms, please let me know and I will check on the mms for google voice for you. Thanks

In the messaging app press the menu button and pick settings.

Now scroll down and uncheck notifications.

If there is a messaging icon on the desktop press the home key and hold your finger on the messaging icon till it turns red and you see the red trashcan and drag the icon to it.