CiviEvent: registering multiple participants using price set that has free and paid options fails

When you have an event, setup with a price set with 2 options :

• member : 0$ fee
• non-members : 4$ fee

then this price set cannot be used with an event that is setup to allow a participant to subscribe extra participants IF the primary participant choose the "member" option.
In that case, when e.g. the second participant is a paid participant, upon prossing the next button, Civicrm will say that the payment options are not setup properly.

I have a forum thread with more information and finding here : http://forum.civicrm.org/index.php/topic,25954.0.html

I have recreated the problem on the demo sandbox also.

I should be possible to use price sets to allow members to register for free, but bring along non-members to an event that will require payment.