The sale needs to be reported only once. This is very common with these interests in the partnerships (K-1 and 1099B).
I personally like to report it only in the K-1 section as my basis information is also there.
IRS is aware of the multiple reporting of these sales and will look for it in the matching program to prevent you from getting a letter from them.
Can you provide an updated answer for this as apparently TurboTax has changed how this is done. I have received 1099B for this sale.
It is still the same way. You can enter the 1099B in the Investments section or report the sale in the K-1 section (which I prefer as the basis is already listed there). <a rel="nofollow" target="_blank" href="https://www.google.com/search?q=How+do+I+enter+a+K-1+(form+1065)+and+1099-B+for+the+sale+of+a+limited+partnership+(individual)+so+that+the+capital+gains+aren%27t+listed+twice+in+Turbotax%3F&rlz=1C1ARAB_enUS463US561&oq=How+do+I+enter+a+K-1+(form+1065)+and+1099-B+for+the+sale+of+a+limited+partnership+(individual)+so+that+the+capital+gains+aren%27t+listed+twice+in+Turbotax%3F&aqs=chrome..69i57&sourceid=chrome&ie=UTF-8">https://www.google.com/search?q=How+do+I+enter+a+K-1+(form+1065)+and+1099-B+for+the+sale+of+a+limited+partnership+(individual)+so+that+the+capital+gains+aren%27t+listed+twice+in+Turbotax%3F&rlz=1C1ARAB_enUS463US561&oq=How+do+I+enter+a+K-1+(form+1065)+and+1099-B+for+the+sale+of+a+limited+partnership+(individual)+so+that+the+capital+gains+aren%27t+listed+twice+in+Turbotax%3F&aqs=chrome..69i57&sourceid=chrome&ie=UTF-8</a>