I changed jobs in 2018 and over paid 401k by $4500. I contacted my plan admin and withdrew the funds and received 1099R. I entered the 1099R with Code P (kind of confusing because if refers to 2017). It appears to have updated my 2018 taxable income; however, turbo tax shows that i have an error with the excess contribution and will not let me file.
You have taken the right steps to have the excess distributed and included the amount of the excess deferral on your 2018 Tax Return.
There is currently an e-filing issue within TurboTax related to excess contributions so you will need to mail in your return. You can check out this TurboTax FAQ for more information: Excess 401(k) Contribution Preventing E-filing.
So... now it is 2020 and I received the 1099-R related to the excess 401(k) I contributed last year that I have also filed as Miscellaneous Income last year. Do I still need to report the 1099-R that came this year or do I just hang on to it?
If you added the income to your 2018 tax return you do not need to report the 1099-R you received for the distribution.