Difference between build 198 & 200

 
I have designed a module using tick data simulated from each minute bar stored in MT4 on buile 198, but after my recent login and upgraded to build 200, the result of my module changed quite a lot. By examing the history data of 1M EURUSD, I found no difference in source data. The only thing I can wonder now is the way MT4 simulates tick data using 1M bars in build 198 & 200. Is there any difference??? Thanks.
 
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4. Tester: Imrpoved fractal modeling of a bar. Now more smoothed patterns are used to model price movements;
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Reason: