In order to merge Gerber files of PCB using Cam350 12.1v:

First of all, you should “import Gerber file” with Cam 350 12.1V correctly, then “File-Exprort-Gerber Data”. That’s to say, you will get the Gerber file with a “gbr” extension;

Secondly, opening the “PROTEL” and creating a new PCB file, clicking “File-Import”, choosing “Batch Gerber” and importing the Gerber file finally.

If you still have questions, please do feel free to ask Shenzhen Grande.