Enumerable.Repeat for reference type objects initialization

Using Enumerable.Repeat this way will initialize only one object and return that object every time when you iterate over the result.

Will those objects have the same address in memory?

There is only one object.

To achieve what you want, you can do this:

Enumerable.Range(1, 50).Select(i => new A()).ToArray();

This will return an array of 50 distinct objects of type A.

By the way, the fact that GetHashCode() returns the same value does not imply that the objects are referentially equal (or simply equal, for that matter). Two non-equal objects can have the same hash code.

Just to help clarify for Camilo, here's some test code that shows the issue at hand:

void Main()
{
    var foos = Enumerable.Repeat(new Foo(), 2).ToArray();
    foos[0].Name = "Jack";
    foos[1].Name = "Jill";
    Console.WriteLine(foos[0].Name);    
}

public class Foo
{
    public string Name;
}

This prints "Jill". Thus it shows that Enumerable.Repeat is only creating one instance of the Foo class.