I think I understand what you are saying in that trader #1 buys 10 @ 660, and later trader #2 buys 10 @ 670 so if that’s their first purchase those are their averages.
What you don’t want to see is 20 @ 665 as your average when you copy the second trader?
Yes you are totally right, I had some problem to see it but thanks to you now I get it. So absolutely no impact overall, only that I will have to keep track on a separate excel file how much I have invested from each trader for this position
So I can stick with my strategy ! Thanks a lot
Does this (these) trader(s) have an eToro account? That would make life a lot easier. 
haha good question ! 
they might have but spread and overnight commission are not the same in etoro 
There isn’t any overnight commission in Invest in either T212 or eToro?
Spreads are raw in T212, and I think US in eToro.