Twodoku

Twodoku is a combination of two Sudoku grids with one common block. Each of these two puzzles cannot be solved separately; there is only one common solution.

Rules: Two regular 9×9 Sudoku grids have one block in common. None of these grids can be solved separately, but all of them together have a unique solution.
In each cell of the 9×9 grid, enter a number from the range 1–9. Each number must appear exactly once in each row, column, and block.