If all model scores are multiplied by 2, will the ROC AUC change?

If two objects are equal according to equals() and have the same hashCode(), but different identityHashCode(), then when inserted into a HashMap, they will be considered as the same key.

HashMap uses the methods equals() and hashCode() to determine key equality and to place keys into buckets. identityHashCode() is a hash based on the object's memory address and does not affect HashMap's behavior.

Therefore:

• When inserting a second object with the same hashCode and equal to the first object according to equals(), it will replace the value associated with the first key.
• The HashMap will not have two entries with these keys, as they are considered equal.

Example:

Map<Object, String> map = new HashMap<>();
Object key1 = ...; // equals and hashCode match key2
Object key2 = ...;

map.put(key1, "value1");
map.put(key2, "value2"); // replaces the value for key1

System.out.println(map.size()); // 1
System.out.println(map.get(key1)); // "value2"

Thus, identityHashCode does not influence HashMap's behavior; only equals and hashCode are important.