Vase makers marks

Thought this was interesting, I purchased this small cut glass bud vase



Which was marked as such



Obviously Tiffany have glass companies to manufacture for them, but I wouldn't have expected the vase to carry both marks.



Do you think this was intentional or an error? would you expect to see the retailers and manufacturers marks together?

I've a Royal Brierley catalogue, c.1935, that states "See the safeguard of quality marked on every piece... the name "Royal Brierley" - so Stevens & Williams, owners of the Royal Brierley Crystal trademark, may have been one of the few glassmakers not to bow down to the rebranding demands of large retailers.

Nice thought, unfortunately they had to bow down to cheap imported glass and have sadly gone the way of all my local glass companies. I can remember the Stevens & Williams factory in operation its know housing called something like Crystal Drive I think. Stuart, both the Webbs, Chance and numerous others were all within a 10 mile radius of where I live