Clouds are clouds and mallards are mallards.
To me the ducks and clouds on the Mt Washington glass and Legsy’s glass are more similar to each other than most depictions of ducks and clouds, I think it’s the way the moon is shown
No, they are not identical, but maybe there is a connection.
This “Royal Flemish style” vase with ducks (no clouds)
https://www.cmog.org/artwork/royal-flemish-type-vase is an “imitation of Mt. Washington” by the Harrach glassworks, 1880-1900, ref From Neuwelt to the Whole World page 37.
Maybe Leggsy’s vase could be Mt Washington (nothing is impossible) or possibly an imitation by Harrach…or other. If it was mine I would be interested if it was an imitation of Mt Washington, even if the actual maker remained unknown.
It’ll be interesting to see the other side, and maybe a closeup of the duck so you can see the enamelling.