You question was slightly confusing. Typically if a lease is broken, the tenant is responsible for rent until the lease expires or until the home is re-rented, whichever comes first. At the end of your statement, you indicated that your roommate had already paid rent. The landlord is not entitled to double rent...if the rent is paid, it is paid. Now, if the roommate left, and you didn't give enough notice to last through what your roommate paid and there is still time left, you will be liable for the time after the rent is paid and for which the notice ends.
Answered on Jan 15th, 2013 at 8:18 PM