Using XOR operator for finding duplicate elements in a array fails in many cases

Question

I came across a post How to find a duplicate element in an array of shuffled consecutive integers? but later realized that this fails for many input.

For ex:
a

Answer 1

Although the answers provided here are good, yet I'd like you to refer the answer by Mohit Jain if there is an ambiguity.

The fact variable xor variable = zero can be used to locate the duplicates present in the array precisely and easily. Hope that helps!