Question: anyone has encountered inconsistent lift/drag after copying and mirroring?

[Csen]

When building a drone/heli type of rotation propeller setup, I found that occasionally after copy paste and mirroring of a complete rotor assembly to a different location, the copied unit would have a different rate of ascend compared to the original. Has anyone encounters this? Now I am using easy scale mod to scale everything roughly by half. My current theory is that the scaling is introducing decimal points that are rounded during copying and mirroring. I will do some tests too but would like community input. Thx.

Update with examples.
Both units are first made in the middle of the sandbox. Moved 6 units to one side then the moved copy was mirrored. You can see that the unbalanced version will slowly began to go out of balance. The balanced version will stay hovering in stable setup for a much longer time.

Unbalanced: https://steamcommunity.com/sharedfiles/filedetails/?id=2103536917

Balanced: https://steamcommunity.com/sharedfiles/filedetails/?id=2103538169

 

[Csen]

I figured it out!. The steering hinge is the culprit. the steering hinge twists whatever it connects by a little bit when the machine starts (very little maybe half a degree) when mirrored this causes changes the pitch of the blades. Just flip half the steering hinges around and reverse the directions would cancel out that little twist after mirroring. This solves the problem.