There was a notion among some folks who lived around the Medeterranian back a few millennia ago that local gods would 'steal' the worship of people who came to live in their territory by convincing those people that the local gods were really the gods those people knew from somewhere else. Of course, the local gods might really be inimical to some of the things that the people believed in, but as long as they could get the people to offer them sacrifices and prayer it made the local gods stronger, and they could then suborn the people even more.
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Quaint superstition? Maybe.