Duplicating custom OSL shaders makes rendering disfunctional

[dralois]

Duplicating a custom OSL shader leads to the appleseed / OSL (?) error: error | error loading memory compiled shader 'NodeClass', 'ShaderName' while rendering. If the same shader is compiled twice instead, it leads to the same error while rendering, as well as a blenderseed internal error: [appleseed] ERROR: Failed to unregister class <class 'blenderseed.utils.osl_utils.'NodeClass''>: unregister_class(...):, missing bl_rna attribute from 'RNAMetaPropGroup' instance (may not be registered). This can be reproduced with any custom shader in Blender 2.82a, with the latest blenderseed build. The same issue does not happen with built-in shader nodes such as asPlastic, asStandardSurface, etc.

[dralois]

Further research into the issue: The problem most likely stems from OSL not allowing the same shader to be added twice, which does happen if a script node is duplicated.