Do you have any proof of that? They run on different speeds, iPad 1GHz, iPhone 0.8GHz which is just related to battery life. Other than that, if I remember correctly, at the teardown, the pictures showed identical part codings and no new element on-die which was not there on the iPad. It even tells the clock speed as 1GHz on the iPhone even though it is clocked at 80%... [...]
Teardown iPhone 4S at ifixit.com shows
"A5 processor is the APL0498"
Teardown iPad 2 at ifixit.com shows
APL0498 in the picture (it is upside-down but I figure you can read it).
...in other words, it will be hard for you to back up your claim that they are different.