Why do I have different results testing my EA in different MT4 platforms?

 
Why do I have different results testing my EA in different MT4 platforms?
 
Probably different historical data, so of course possibility of discrepancies.

Also, if you test with "current" spread, you will get a different result every time even if you are using exact same settings and exact same datafeed!
 
A good lesson for us in designing a strategy; ensure profitability under all market, broker conditions.....