I developed a trading script and trained it with walk forward over a set period of time. I did quite a bit of testing and changing until I got that result. So I created a copy of the C file as I wanted to develop it further without losing what I already had.

You would expect that this identical copy of the code, being trained with the same time period and currency pair gives you the same result. But in fact the training result is significantly worse than when I train the original.

I am at a loss. Any ideas?