Hi John -
As I think you've discovered, we don't currently support the ability to create two, distinct [Measure Names] and [Measure Values]. We have had some user requests for this functionality - you can add your voice over here: http://community.tableau.com/ideas/1185
That being said, your best bet is just to create two worksheets - one per chart. Then, drop these suckers into a Vertical Layout container in your dashboard.