Doppelgänger

Normal Sudoku rules apply. Grey shaded areas are clones, i.e. digits must appear in the same relative position in each of the four grey regions. For example, the cell R7C1 has to contain the same digit as R3C3. Digits in a cage do not repeat and sum to the clue in the top left. The digits on a gray line form a palindrome, i.e. they read the same forward and backward. Digits on an arrow sum to the digit in the circle from which the arrow emerges, i.e. the 1-cell arrows indicate two positions of the identical digit.