newbie question about blender texture to GoB

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Hello,
I got a fancy model in blender with a lot of material, I send it to zbrush via GOB and when I ship it back to blender it give me a duplicate of the model with no material on. What I would love to do it's just make some change of the model and apply it to the existing model in Blender with all the materials in place. Is it possible?
Thank you