Quote - >>> but if in one pose inside the lot someone renamed the PoserSurface node you may got an extra PoserSurface node.<<<

That might be the problem, then ... I've seen nodes renamed, but the main issue here is that the Poser Surface Node was renamed as well, which as far as I know isn't possible within Poser itself because the Poser Surface Nodes are named that way by default.

So it seems to me that the "bug" is in the pose files, and not Poser.

Content creators often rename the nodes, i have plenty of samples in my runtimes, usually it's copyright message, i don't have checked if they rename the PoserSurface node .

If Poser can handle only one PoserSurface by material but can create several of them, the bug is in Poser, the pose file is just here to show it,

Poser must warn the user as soon it read the second PoserSurface definition or take only the first in account and don't create the superflous

Or maybe SM is preparing the multilayered material room ??