Unique Rectangle Type 1
Two digits at the four corners of a rectangle would give two solutions. With the spare candidates in one cell only, those two digits go from that cell.
How it works on this board
Assuming the target lets the highlighted pattern swap into a second solution
3
6
2
7
1
7
2
9
3
1
9
3
2
6
7
1
8
4
9
1
8
4
6
7
3
4
6
5
2
1
9
1
8
3
5
7
6
7
5
8
4
9
2
4
2
3
7
9
5
1
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