I don't know what to believe!

I think I am in need of a new scale. I step on the scale forward and it reads one number I turn around and step onto the same scale backwards and it says I'm 50lbs heavier. Now my big dilemma is which is the accurate weight. Obviously I don't want to be the higher weight, but is it possible that a scale can add 50 lbs just because I'm in a different position or remove it if I'm in a different one.

If stepping on the scale forward is accurate (forward is the number I recorded on day one) then I lost 20 lbs in two weeks.... I don't know what number to believe!