To me I don't see it as something strange rather a marketing strategy to also help boost their platforms. For instance; there are some gambling site which accepts wide range of cryptocurrency on their site and that is just means of deposit, it doesn't directly mean that they must be collaborator to enable them list.

However, in other to attract real time players seeing that shuffle is becoming very large they have to includes most of the big gambling site token and coin to boost their usage or increase their traffics by offering some set of discounts to them, since the gambling industry is becoming more competitive nowadays. Everyone owner of gambling site is looking for a way to attract attention of people to their site by offering series of opportunities to the others community in other for them to show interest in their gambling site.

Though I could be wrong about the whole thing, maybe who knows if they are in collaboration as you said, only them can clear the air about their similarities and the offers for those holding Shuffle tokens.