Hypothetically, could a Duke (UK) be created if there is already an earl of the region?

For instance, if there is an earl of Es but no duke, could the Queen make a Duke of Es or would it have to be a completely new region. Similarly, does a holder of a tittle, say a Duke, also hold all of the subsidiary tittles likes marques, viscount and earl? Does hereditary or life peerage make a difference?