Didn't you also get a Copy B and Copy 2? Just report one of them 1099R.
It doesn't matter what copy of the form you have, it needs to be entered on your tax return. Since you have copy "C", there was likely a copy "A" and "B", but they would all report the same information.
Enter Form 1099-R one time regardless of how many copies of the same form are received.
Here's how to enter the information on your Forms 1099-R:
In TurboTax Online, under Wages and Income:
See this help article for more information.