I only have about 20 pounds to lose, but I have a habit of getting obsessed about the numbers. Of course I actually compared the scale after it said I lost four pounds with my bathroom scale, and it was right. I didn't believe it at first, since I didn't see a number to prove it! I am already down about 8 pounds. But, I know it's just water weight..so I won't get too crazy about it. But, this scale is really great for those who get obsessed with numbers, The music actually gives you a little boost of happiness. Sounds silly, but to me it does.
I am not sure about why the previous person weighed on both sides? I can't answer your question about why the scale would do that. But, each side is one individual..I really didn't have the desire to test both sides to see if they said the same weight...