Explicit interface implementation related with an IEnumerable<T> implementation?

Question

Why in this MSDN example is needed the GetEnumerator1 method?

// Must implement GetEnumerator, which returns a new StreamReaderEnumerator. 
public IEnumerator<string> GetEnumerator()
{
    return new StreamReaderEnumerator(_filePath);
}

// Must also implement IEnumerable.GetEnumerator, but implement as a private method. 
private IEnumerator GetEnumerator1()
{
    return this.GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
    return GetEnumerator1();
}

Answer 1

No need, we can just use

// Must implement GetEnumerator, which returns a new StreamReaderEnumerator. 

public IEnumerator<string> GetEnumerator()
{
    return new StreamReaderEnumerator(_filePath);
}

// Must also implement IEnumerable.GetEnumerator, but implement as a private method. 

IEnumerator IEnumerable.GetEnumerator()
{
    return GetEnumerator();
}

instead.