It should be "Call of Duty: Modern Warfare 2"

I'm pretty sure it's official release name does not say Call of Duty at all. IIRC they were trying to split the MW and COD IPs at that time. I remember they talked about it on the bombcast.

Here's a news story about it from around launch. It sounds like Infinity Ward didn't want to put the Call of Duty name on it, but someone at Activision put it on the box art anyway. If you look up videos of the title screen for the game there's no Call of Duty anywhere.

http://www.cinemablend.com/games/Modern-Warfare-2-Box-Art-Reveals-It-Call-Duty-Game-18583.html

Modern Warfare 2 is when they started moving away from the COD name, but Activision reverted afterwards.

As someone who has been listening to old Bombcasts in the car, it's Modern Warfare 2. They talked about the title, would it have "COD" on the box, etc. at the time. Infinity Ward wanted to call it MW2 and treat it more as a sequel to COD4. (This was still during the time with "off year" games like World At War)

@kingmayuke:http://www.giantbomb.com/modern-warfare-2/3030-24713/forums/activision-not-changing-modern-warfare-2-title-aft-251948/?page=1/