Dwaparan is believed to be the lord of Dwapara Yuga. The term Dwapara also has the meaning doubt. Yet another meaning is third. It is said that Dwaparan is a friend of Kali (as in Kali Yuga). They are friends because Dwapara Yuga and Kali Yuga are nearby.
Shakuni is Mahabharata is an avatar of Dwaparan. After death, he merged in Dwaparan. There is no further information about Dwaparan in Puranas.
In the story of Nala and Damayanti, Dwaparan is friend and helper of Kali. These two evil characters combine to create serious difficulties in the life of Nala. Due to them Nala experiences hell while living on earth.
Dwaparan and Kali help Pushkara to defeat Nala in an already fixed dice game. Dwapara enters the dice game board and creates doubt in the mind of Nala. Dwaparan also takes the form of a bull and becomes a pawn for pushkara.