Around 1930 a swiss citizen named Charles Hertig, has established in Portugal and started selling watches, mostly Certina. At some point he started rebranding Certina watches to Hertig (in the OP watch is possible see that the caliber is a KF321, a Certina movement) and selling them under that name.
These watches are, in fact, Certinas rebranded Hertig and are very common in Portugal
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