Given a collection of numbers, nums, that might contain duplicates, return all possible unique permutations in any order.
Example 1:
**Input:** nums = \[1,1,2\]
**Output:**
\[\[1,1,2\],
\[1,2,1\],
\[2,1,1\]\]
Example 2:
**Input:** nums = \[1,2,3\]
**Output:** \[\[1,2,3\],\[1,3,2\],\[2,1,3\],\[2,3,1\],\[3,1,2\],\[3,2,1\]\]
Constraints:
1 <= nums.length <= 8-10 <= nums[i] <= 10