You do not qualify for a credit for taxes paid for other states because you were a part-year resident of two states.
You can only claim a credit if you live in one state and work in another state at the same time.
Indiana will tax all your income while you lived in Indiana. Alabama will tax all your income while you lived in Alabama.
If your employer made a mistake and withheld Indiana tax for the whole year, you would get a large refund from Indiana because you are reporting income from January–April, but withholding from January–December.
That is still not double-taxed income. That is an adjustment of your part-year wages.
If you reported this wrong, you can file an amended tax return.
