Two months ago, they said that the dual login for joomla_ext will get into 1.1.2RC1. However, after two months, JFusion still can not allow mulitple Joomla to be sync. Maybe I misunderstand what this component is about. It is only a bridge with broader capacity.
Yes dual login between Joomla installations is available with JFusion. If you have questions: the best place is to ask on our support forum. If you suspect you have found a bug: please report it on our bug tracker and we will fix it for you asap.