in the Main() of the vector program they write:

Vector v1 = GetVector("vector1");
Vector v2 = GetVector("vector1");

I believe the second line should be : "vector2"

Actually I am not sure if that is a semantic error. It is just a typo?

It looks like a typo to me, too. But it does not matter. The only thing the string is used for is to be part of the prompt for the magnitude and angle.