Fixing a bug where the duplication check depends on the order of fields

Fixes #41010

BUT: Abuse of this bug is actually quite common, fixing all the occurances in the fpc repo so make all ran through took me already >2h. So if this is merged probably any project of non trivial size will break...

Case in point, the pipeline still breaks because I'm not on linux and couldn't test the fullcycle build like the pipeline does :)