Filing for a deceased person that passed before 2nd stimulus checks were given, turbo tax keeps adding the $600 to the refund - is this accurate? How can I change?

It is accurate. Read the answer to Q B12 at the link below.  

https://www.irs.gov/newsroom/recovery-rebate-credit-topic-b-eligibility

Yes.  For deceased individuals see the second question under Eligibility.  If they died in 2020 they still get it.

https://www.irs.gov/coronavirus/second-eip-faqs