There are two films with the ducks:
Magic in the Mirror (1996)
IMDb synopsis:
Mary Margaret Dennis' (Jamie Renée Smith), imaginary friends Bella and Donna tell her to make a sculpture of Principal Mallard (Eileen T'Kaye). Meanwhile, her mother, Sylvia (Saxon Trainor), is experimenting with opening doors into other universes with a machine called the Doppelgänger. She succeeds and asks her colleague, Laszlo Tuttel, to her place for dinner to celebrate. Meanwhile, Mary Margaret has gotten into her Great-grandmother Margaret's book of flowers and discovers one with strange berries that she takes into her room. Something weird happens, and Bella and Donna disappear through Mary Margaret's newly-acquired hand-me-down mirror. At dinner, Mary Margaret gets into trouble when Bella and Donna throw tea on Mrs Tuttel. She is sent to her room and discovers that there is a new world behind her mirror. There she meets lazy Mirrorminder Tansy and Mirror Master Melilot. She also attracts the attention of the tea-obsessed Drakes, ruled by the evil Queen Dragora, who wants her because people make the best tea: They get steamed in boiling water for a minute. And, she is out for the berries.
Here's Part 1 on YouTube:
http://www.youtube.com/watch?v=wT_Ur0je7bM
Magic in the Mirror: Fowl Play (1996)
IMDb synopsis:
Mary Margaret (Jamie Renée Smith) is faced once again with the Drakes as Laslow Tuttel opens up a doorway into the Mirrorworld using the Doppelgänger. This results in Queen Dragora escaping into the "people world" with her two off-siders, Dabble and Swanson. To combat this, Mirrorminder Tansy and Mirror Master Melilot "violate a mirror" (in other words: cross over).
Here's Part 1 on YouTube:
http://www.youtube.com/watch?v=NSBXGiwquQM