Are you asking specifically about the mortgage interest as a landlord versus a homeowner, or all your deductions?
As a homeowner, you are allowed to deduct interest on your primary and secondary residence. This is recorded on Schedule A as an itemized deduction and replaces your standard deduction.
As a landlord you can deduct your interest as an expense that offsets your rental income. It is important to know that most landlords are considered passive by the IRS, so that means that you can not claim a net loss for the rental property. So if your rental income is $12,000 and your interest is $10,000, takes are $3000, and depreciation is $2000, then you would have a net loss of $3000. Chances are good that unless you are a real estate agent, this will end up being limited at zero and you would have $3000 of losses that you essentially will lose.
So in both cases you can deduct the interest, but depending on your situation, you may end up losing a little.