I've noticed this problem, using jquery 1.4.4 and jquery ui 1.8.7: if you setup a resizable element with both the alsoResize option and the helper option, when you try to resize it what you get is that the helper is shown as it should, preventing the immediate resize of the resizable element, but the element specified in the alsoResize options is resized immediately and not on resize end.
This looks like an incorrect and inconsistent behaviour to me. Here is an example:
http://jsfiddle.net/4LEGA/