Normal sudoku rules apply in both grids. In each grid, the circles contain a complete set of the digits 1-9. For each pair of circles in the same position in both grids, the digit is the same. In one of the grids, the value of the cell is double the value of the digit. In the other grid, the value is unchanged. The doublers are not necessarily all in the same grid. It is up to the solver to determine in which grid each digit is doubled. Digits cannot repeat in a cage. The values of the cells in a cage must sum to the small clue, if given. Even if the cage total is not given, two cages in the same position in the two grids must contain values summing to the same total.