Agnostics

[wiploc]

... the possibility of a conditional belief-- If A, then B; if not A, then not B.  For example, if the universe is a created thing, I'd be willing to call whatever philosophical principle or creative impetus created it "God."  Since I cannot know whether the universe is a created thing, I have a belief state of AnotA.

Your example does not support your claim.  I assume that we can all stipulate to conditional beliefs. 

• If you are taller than me, then I am shorter than you, but if you are not taller than me then I am not shorter than you.
  

That doesn't prove, or tend to prove, that people can believe both A and not-A. 

Note that I'm not taking a position on your claim.  I'm just pointing out that your example doesn't support your claim.