Yes, duck.com came as an asset in the unrelated On2 acquisition (On2 used to be known as Duck Corp). But it just sat there (pointing to this Duck Corporation history page) for a long time.

I first inquired about it on 11/4/09. After several attempts, I got back a response "from management" on 3/25/10 that they didn't want to sell it. Understandable.

Now http://www.on2.com/ points to a Google explanation page about the On2 acquisition, yet http://duck.com/ points directly to Google search.

Google owns lots of domains that don't point anywhere, or not to their main search page. That means there was an affirmative decision somewhere along the line to redirect that particular domain to their search product.