Prolog

I am learning prolog and one of the questions that I don't understand is

What relationship between X and Y does the query

$?-$ parent$($Z$,$X$),$ parent$($Z$,$Y$),$ X $\backslash =$ Y$.$ imply?

Note: that $\backslash =$ means $$not equal to$,$ i$.$e$.,$X is not equal to Y$.$

Note: that both of these queries of will produce duplicates $$ that is okay

Can you also give an example of this?