Landlord "accidentally" double leased our apartment for the fall?

Hey this is my first time posting, but i wasn't sure where to turn. So i'm a college student and just finished up freshman year. I recently signed a lease for an apartment for next fall and have a binding contract stating that we have the apartment, what the rent will be, terms of the agreement, etc. However, after signing this contract with my roommate on June 7th, i got a call today from our future landlord saying that he had actually already rented our apartment to another tenant on June second and, due to an error on his part, he signed us to the apartment as well. When he informed me of this, he was very apologetic and eager to get us into another unit. However, I'm not happy at all with the situation and feel like we were mislead due to the landlord's idiocy at our own cost. What can we do? should we just accept the fact that he messed up and go with a different unit? i don't think we have any chance of getting our original desired unit since there is already a lease on it that was signed before ours, but we feel like we've been defrauded! help!