Box 12 Code DD is for informational purposes only - it represents the employer cost of health insurance but it doesn't affect the tax return.
Box 12 Code W represents HSA contributions. While the change in your tax return is likely to be very small (if any) due to the amount, having this code would trigger Form 8889 to be completed. So, you may want to amend the return just avoid any sort of auto-generated notice from the IRS.
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