During QA validation of the Oakley Prizm catalog, each imported product identifier should appear only once. Given a list of catalog IDs, determine whether any identifier occurs more than once.
Return True if at least one duplicate exists. Return False when every identifier is unique.
Implement contains_duplicate(entries), where entries is a list of strings. The function must return a boolean and must compare identifiers using exact, case-sensitive string equality. An empty list contains no duplicates.
def contains_duplicate(entries):