Ni hanchan or two hanchan is a format, where as the name implies, two hanchan are used to determine a result. For competition play, especially when using tournament brackets, single hanchan is inadequate to determine a winner due to luck factors. So, the match is extended into two hanchan for a slightly more thorough result.
The result of each hanchan includes placement applied by uma. Especially in the second hanchan, players will have to consider the effects of the uma bonus when determining final placement. The added difficulty places an even greater emphasis and pressure on game strategy. The format still allows the player scoring a 4th placement in the first game to still have a chance of winning in the second hanchan.