Can the same key be used for different elements in a Map data structure?

In a data structure like Map (for example, java.util.Map in Java), keys must be unique. If you try to add an element with a key that already exists in the Map, the old value for that key will be replaced with the new one.

That is, you cannot store multiple elements with the same key. If you need a structure where one key can correspond to multiple values, you can use, for example, Map<K, List<V>> or Multimap from Guava libraries.