No -- there's nothing to override. You can be eligible for both.
You're eligible for an age deduction of up to $12,000 if you were born on or before January 1, 1959. See Taxpayers Age 65 and Older in the Form 760 Instructions. This deduction is taken on line 4 of Form 760.
For 2023, you're eligible for a military benefits subtraction of up to $20,000. This is claimed on Schedule ADJ, and the subtraction will appear on line 7 of Form 760.
According to 60, Military Benefits Subtraction in the instructions linked above:
This subtraction is not allowed if a credit, exemption, subtraction, or deduction is claimed for the same income pursuant to any other provision of Virginia or federal law.
This means you can't "double-dip" tax benefits based on your military-related income -- that is, you can't claim more than one type of tax benefit on this specific income.
Since the $12,000 age deduction applies to all income, there's no double-dipping going on.
