I'm not sure if these have been proposed or noticed yet. The following should also qualify as a multi-solution deadly pattern where uniqueness deductions could apply.
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. . ab | bc . . | ac . .
. . . | . . . | . . .
. . ab | bc . . | ac . .
If you place an extra candidate, x, in any of the lettered cells, that candidate must be true in order to have a unique solution.
You can keep on extending this as well, so long as you follow the BUG rule within your pattern; i.e. every candidate in your pattern cells if it exists in a group, must show up twice in that group. Consider only the pattern cells in the group when applying this rule. For example, this is another deadly pattern...
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. . ab | bc . ad | cd . .
. . . | . . . | . . .
. . ab | bc . ad | cd . .
...and so is this one...
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. . ab | bc . . | . . ca
. . . | . . . | . . .
. . ab | bc . . | ca . .
-------------+------------+------------
. . . | . . . | ca . ca
. . . | . . . | . . .
. . . | . . . | . . .
...but, not this one (the c candidate only shows up once in cols 7 & 9 in the pattern cells)...
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. . ab | bc . . | . . cd
. . . | . . . | . . .
. . ab | bc . . | cd . .
-------------+------------+------------
. . . | . . . | ad . ad
. . . | . . . | . . .
. . . | . . . | . . .
You can kind of envision some of these patterns as mated xy-chains, or a cycle pattern that obeys the BUG rules.
You can get some interesting uniqueness cases out of these, for example...
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. . ab | bcx . adx | cd . .
. . . | . . . | . . .
. . ab | bcx . adx | cd . .
...here, you can remove x from all of the unlettered cells in the center box, because you know that x must be true in one of the lettered cells to avoid multiple solutions.
[edit: added BUG's two-or-none rule for pattern building & substituted term "deadly pattern" for "uniqueness setup."]