Sometimes it takes a while for the offset payment to register and the same amount ends up being offset from both your Federal and State Refunds.
You will need to contact whichever agency got the "double payment". If it was the IRS, they will eventually issue you a refund, but you can also contact them at 1-800-829-1040. If it was the State of CA, you can click here for contact info: https://www.ftb.ca.gov/aboutFTB/contact.shtml.