Remember that a movie is at least a mere couple
hundered thausand cels. When you have them all
at your disposale, you may well choose to waste
a few to do a more interactive (hum..) exhibition.
After all, a single scene can have anywhere up
to a couple hundered cels nearly identical. If
you need to trash one every 6 months, you may
still have enough for 50 to 100 years... and just
with one scene.

Cheers,
Yann Stettler

PS: They may also be exhibiting copies : why not
ask your employee to draw a few more for 
exhibiting ?