In Relational database, Functional dependency is denoted as X -> Y where X:Determinant and Y: Dependent. So, as per the concept the value of Y gets determined by the value of X.
If value of X gets duplicated, then in those rows value of Y shall also gets duplicated correspondingly.
If the determinant X value is unique (different) then the dependent Y could have any value meaning:
for same X , value of Y should be same.
for different X, value of Y could be same or different.