Inaccurate spread in MT5 backtester


I'm backtesting a strategy with MT5 in "Real Ticks" mode. I'm using a broker that offers 2 different Account Types: Type 1 with higher spread and without commission and Type 2 with lower spread + commission. I'm backtesting using Account Type 1.

However, when comparing real results vs. backtest result there's always a difference in the open and close price despite the same open and close time.

When backtesting in visual mode, the spread that is displayed is the one of Account Type 2 but without commission. Is there any way to fix this?

I already tried to modify the symbol properties before backtesting by changing the spread type from "floating" to a fixed number. But that does not have any effect. 

Any help is appreciated.

Maybe it is a glitch. I notice errors all the time with MT5 or 4. Unfortunately who know the answer. 
Fixed spreads can be very tricky.