Tandem-rotor helicopters, such as the Boeing CH-46 Sea Knight and CH-47 Chinook, are helicopters with rotors distant by more than 10 m.
It seems unlikely a single rotor could sustain the force moment created by the failure of the other rotor. On the other hand it seems to me it would be difficult to have one rotor in autorotation and one powered.
If this is possible, how would the pilot fly the helicopter? If it's not possible, why?