BuildDupeInfo not always created

[AlexG345]

Describe the bug

Gmod version: 2026.05.08, only advdupe2 enabled.
PR: #540

I noticed that when spawning a dupe using the duplicator then duping it with advanced duplicator 2, BuildDupeInfo never gets created. Even after re-copying, saving, and pasting the dupe (all using advdupe2), BuildDupeInfo still didn't appear. I think this means that any dupes that went through the vanilla duplicator, even just once, will inevitably suffer from sag, since the vanilla duplicator doesn't save the BuildDupeInfo table. No idea when that started happening though (or was it always like that?).

How to reproduce the bug

Spawn a car using the vanilla duplicator, move one wheel, then copy paste the car using advdupe2. The wheel stays stuck in the wrong position.

[AlexG345]

I looked around for a bit and I think that this is all caused by Advdupe2 modifying the functions from the constraint table, but not the ones from duplicator.ConstraintType.

advdupe2/lua/advdupe2/sv_misc.lua

Line 84 in 2dd4514

constraint[name] = function(...)

At the time the functions are modified by advdupe2, their "old versions" have already been saved in the duplicator.ConstraintType table I believe.