I am married but my husband I are filing separately because I owe money to IRS. I itemized my deductions and see he has to as well. He claims same ones I already have?

When entering itemized deductions on two separate tax returns, the amount of the deductions being reported cannot be greater than the total amount paid for the deduction.

For Example - If you had Mortgage Interest of $1,000 then only that total amount can be entered between the two tax returns.  You cannot enter $1,000 for Mortgage Interest on one tax return and then enter $1,000 for a Mortgage Interest on the second tax return,