This potential DuckTales story might be an homage to GI Joe's The Synthoid Conspiracy and possibly mixed with DT1987's Send in the Clones.
The Ducks and McDucks have war games, never knowing that Ma Beagle is working with Magica to sabotage the festivities. Magica also presents evil clones of much of Duckburg's elite, including Scrooge, M'ma Cabrera, Roxanne Featherly and such. Mark Beaks doesn't approve of this and Ma Beagle demonstrates the neutralizer as the only way to stop these evil clones. The Mark Beaks clone melts like the Wicked Witch of the West.
Fake Scrooge cuts much of the funding and is even mean to his family. Magica begins the next phase of her scheme: Kidnap the triplets and replace them with evil clones.
Magica goes far to taunt "If you're family wants to rescue you, they first to notice you are M.I.A.!"
Fake M'ma tries to have Donald and Della killed by Gizmoduck. Gizmoduck instead provides the Duck Twins a safe passage to escape.
The triplets manage to break out and race to warn their mother and uncle. At the Beagles occupied McDuck Manor, the Beagles seem to relish in their victory.
Mark Beaks begrudgingly helps those who are aware of imposters and says "Will the REAL Huey, Dewey and Louie please stand up?" The fake triplets try to make excuses.
Having provided the family and their friends weapons, Beaks leaves.
Our heroes storm McDuck Manor. Fake Scrooge fights Webby. Della and Donald fight the fake triplets. Fake Scrooge is forced back by the real Scrooge. Ma Beagle activates the neutralizer never knowing it's set at maximum, killing all the clay clones made by Magica's magic. Fake Scrooge gives out the Evil Witch's death cry from Snow White while melting. Fake Huey wails, "I'm melting! Save me, Magica! What a world!"
Fake M'ma says "People of the Duckburg Police Force; Under our new structure, Ma Beagle and Magica" melts away "are hearby recogniiiiiiiized as our frieeeeeends."
The fake Mayor of Duckburg says "From this time forward, all of Duckbuuuurg, is to be renamed Beaglebuuuuuuuuuuur-!" and melts away.
Ma Beagle is blasted away like Team Rocket via Magica's furious magic blast.
In the end, everyone is given an engraved apology.