Should the IRelationalOperator.Equals return true regardless of vertex orientation?

Question

I don't recall every having an issue with this method, but I am now. As I understand IRelationalOperator.Equals, vertex orientation shouldn't affect equality and if I take a polyline and reverse orientation, IRelationalOperator.Equals should still return true.

However, I am not usually seeing this: IRelationalOperator.Equals usually returns false although occasionally it will return true after a ReverseOrientation() (very strange--I'm seeing this maybe 1 out of 20 calls).

Is my understanding of this method correct? If so, is this a bug or is there something wrong with my implementation?

IPolyline polyline1; 
IPolyline polyline2; 

//...other code

polyline2.ReverseOrientation();
IRelationalOperator relop = polyline1 as IRelationalOperator;
Trace.WriteLine(relop.Equals(polyline2 as IGeometry));