Can different objects return the same hash code?

Yes, different objects can return the same hash code. This is called a hash code collision.

The hashCode() method in Java or GetHashCode() in C# returns a fixed-size integer value, and the number of possible objects is usually much greater than the number of possible hash codes. Therefore, collisions are inevitable.

It is important that when overriding the hash code method, the rule is followed: if two objects are equal according to the equals() method, then their hash codes must match. But the reverse is not necessarily true — having the same hash code does not guarantee object equality.

Example of a collision:

String a = "FB";
String b = "Ea";
System.out.println(a.hashCode()); // 2236
System.out.println(b.hashCode()); // 2236

Here, different strings have the same hash code.