Accidentally found this bug:

If you duplicate a part (Exp. Left Arm) within a humanoid, the duplicate will remain a humanoid arm, but the original will turn into a normal-studded brick.

That’s not really a bug as much as it is the way humanoids work.

The arm is still within the humanoid and named a different name.

The arm is still within the humanoid and named a different name.[/quote]

Ah, that’s something else then.