Dooku and Sifo-Dyas

Question

I was watching Episode II: Attack of the Clones and when I came to the part where Yoda and the Clones attack. In the movie, Count Dooku appears surprised by the appearance of the Clone Army, going on to say:

That doesn't seem possible. How could the Jedi come up with an army so quickly?

Meanwhile, This Wookieepedia Article on Master Sifo Dyas mentions that:

At a formal gathering upon Perlemian Orbital Facility, Hego Damask—the Sith Lord known as Darth Plagueis—following up on a previous conversation with Sifo-Dyas suggested to him that he should seek the cloners on Kamino and have them grow a human army. Therefore, in order to defend the Republic, Master Sifo-Dyas secretly commissioned a clone army from the aforementioned cloners. Falsely claiming to be a leading member of the High Council while dealing with the cloners and backed financially by Hego Damask, the Kaminoans, using Jango Fett as a template—hired by Dooku—began cloning and training soldiers for the Republic.

and,

Erasing all records of Kamino from the Temple Archives, Dooku's final test his Master provided him was to murder his old friend, Master Sifo-Dyas. Executing the man, Dooku usurped all control of the project for the Sith, using Sifo-Dyas as a cover.

This sufficiently proves that Dooku knew all about the creation of Clone Army.

My Question is: Why does he appear to be surprised in the movie?

Answer 1

When he said that, he was with other separatists, like Nute Gunray. The intervention of the clone army is part of the plan, but, to make the plan work, it is imperative that the separatists trust Dooku, so he simulated surprise.

The Clone War is essential to the rise of Sidious as the Emperor, and for the establishment of a new Sith Empire. But for that, he had to play the separatists' friend:

As Tyranus, Dooku became a Humanocentrist. While he remained a connoisseur of alien art and antiquities, he secretly despised most if not all of the corrupt aliens on the Separatist Council, though he reserved a measure of respect for the Geonosian Poggle.
- Dooku article on Wookieepedia

Answer 2

Also, what happens at the end of Episode II shows us what Dooku really knows. We see him meeting with Sidious in Coruscant, after escaping with the Death Star plans:

Count Dooku: The Force is with us, Master Sidious.
Darth Sidious: Welcome home, Lord Tyranus. You have done well.
Dooku: I have good news for you, my lord. The war has begun.
Sidious: Excellent. Everything is going as planned...

For him the clone army was good news, impliying that he was aware that the clone army was part of Palpatine's plot.