No, liberating restores or creates a new family of the first occupying faction. So for example, if Rome has fallen to another faction, liberating Rome will restore Rome as a faction if it has been destroyed, or spawn a 2nd Roman faction if the Roman faction is still alive at that moment. Some can also be emerging factions, for example liberating Judea creates a Judaic faction) or liberating some towns in Southern Italy will spawn italic factions. The liberated faction will have a military alliance and military access pact with you. So you can for example disrupt your enemy by not occupying some of their towns, but turning them into extra allies instead.