Well, I did some proper scientific investigation. I reckon that this puzzle can't have a uniques solution:

Look at the box where the top-left and central grids overlap (box 9 in top-left grid; box 1 in central grid). There's a 4 and an 8 in it already. Simple elimination means you can place three more numbers, like this:

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`4..`

1..

358

The 6 in r1c9 of the top-left grid (or the one in r4c3 of the central grid works just as well) restricts the 6 in the box we are considering to being in the central mini-column. This leaves 12 possible ways to fill the remaining 4 cells:

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`62 62 69 67`

79 97 27 29

67 69 29 27

92 72 67 69

97 79 92 72

62 62 67 69

Now, a property of Samurai puzzles is that each individual puzzle must be solveable in isolation

once the box(es) that it shares with other puzzles are filled in. But I tried the top-left puzzle in Sudoku Susser with each of the twelve possibilities for box 9, and they all either have no solution, or multiple solutions. Therefore, I conclude the puzzle is unsolveable.

If I've made any mistakes here, please point them out. I would love to be proved wrong about this.