Can a cell phone be connected to two bluetooth headsets at once?

[New Daddy]

Can a cell phone be connected to two bluetooth headsets at once?

What I'm envisioning is to connect my XV6700 to my car's BT headset and my Garmin GPS's BT at the same time.
It's because my car's built-in BT provides much better sound quality, whereas the Garmin GPS lets me call destinations by clicking on the phone number displayed on the screen.
So, I would like to initiate a call by clicking on the GPS screen, let the GPS engage the phone in the call, and speak through my car's built-in BT when the receiver picks up the phone (I can mute GPS so it doesn't get involved in the actual conversation).

Would this scheme work?