Skull badge. Help needed to identify.

[Rofocale]

Hello Everyone,
I show you some photos of a small collection that I have, with the same model to identify.
Apart from the obviousness of the skull, they all have a point in common, they have been manufactured or bought in Portugal.

But that is also the problem. I have investigated the various most important detachments of that country, including the 'Regimento de Lanceiros', the 'Polícia do Exército' and the 'Legião Portuguesa' (during the Second World War) and nothing, not a single reference of this badge.

Two of the badges were manufactured at the 'Casa Buttuller' in Lisbon and I recently visited the store (which is still open), but I could not obtain any information because the old owner had died, and the people who attended to me didn't know the origin of the badge. Any ideas??