A magnetic balancer has close to zero drag so if the prop moves very, very slowly it is as close to being balanced as it can be. If the Dubro shows that same prop as being balanced it's probably just because the Dubro has a lot more drag with the wheels. I have a magnetic balancer that has the same trait as the Top Flite and I trust it a lot. I've never used the Top Flite though but it sounds like the same behavior as mine. If it is then it's nothing to be alarmed by.