BUG Type 2
The spare candidates are the same digit across several cells. One of them must be true, so the digit goes from every cell they all see.
How it works on this board
A pure BUG has two solutions, so at least one highlighted extra candidate is true
6
9
4
3
7
3
8
5
2
9
5
7
2
6
8
7
3
9
9
3
1
6
6
8
9
5
3
4
3
4
8
6
9
9
5
6
4
3
6
4
2
8
5
7
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