The weird thing is that even when Slippage is set to 0 there's still this: Avg trade slippage -0.27$ -3.1p (+0.0p / -3.8p) in 1.50.6. It makes part of the difference ($50) but not all of it. Maybe someone else will be able to find the other cause.

Also you can check the trade logs side by side and look where the differences occur.