I'm not sure about the second deposit issue, but I do know that he does not have to prorate your rent. However, if you pay the full month rent and still move on the 8th, you have the legal right to hold onto the keys until the end of the month since you did pay for the full month use. If you move on the 8th, I would recommend that you check back on the house to see if the landlord rented it for the second half of the month. If he has, then he is required under the law to prorate your rent because he can't rent the same place to two different families at the same time. Please keep all rent receipts to insure that you have proof that you paid for the entire month, this way if he does rent for the second half and still doesn't prorate your rent, you can take him to small claims court and get your money back.