[Brightcolours]

Distortion will NOT vary from copy to copy. ...

That's a statement I find hard to believe. Everything varies, especially centering and resolution. if these properties are variable in each specimen, I see no reason why distortion is not affected.

Also, using the same software doesn't mean the setup for each lens test (site) is identical. The software programmers don't deliver the full hardware equipment, do they? Maybe I'm wrong but a lot of these testers don't appear to have a solid professional background as optical engineer.

I can't help it that you find it hard to believe.