Whenever I dupe a parented prop it destroys all the constraints of said dupe and breaks my advanced duplicator until I restart GMod. I have made sure that my Advanced Duplicator’s SVN is up to date however I still get issues. I have also attempted using different parenting tools.
I’m pretty sure that Super Parent Multi does fine with dupes.
I have about 10ish dupes that are super parented. (all spawn in perfect condition)
So Im pretty sure that this will solve your problem.