Well, whenever some API happens to do something one doesn't expect, the first reflex should always be: "Lets take a minute and look up what the documentation of that API has to say!" (I know, very old-fashioned and not really reconcilable with modern software development techniques. But lets pretend it's the last century and try anyways...)

From the remarks section of the Array.Resize documentation:

This method allocates a new array with the specified size, copies elements from the old array to the new one, and then replaces the old array with the new one.

and

If newSize is equal to the Length of the old array, this method does nothing.

So, documentation FTW....