Closed on new Duplex, leftover tenant lease question?

I just closed on a property where the previous owners told me the leftover tenants lease expired July 1, 2010. Saw this lease at closing, today I told tenant I expected them out by July 1 and they showed me their copy of the lease that Shows dates from Feb 1 2010 thru July 1 2010 but also says in fine print it is a One year lease. I want/need these tenants out by the end of July since I signed up new tenants for Aug 1, 2010. Am i wrong for wanting these people out? Do I have a legal problem here or just some dead beat problem leftover tenats I DONT WANT ?