You should be able to use any number of CartItemSelector controls in a transformation, as long as each has unique ID. However they will not be able to work with each other. Any choices you make in first selector will not save when you click the Add to shopping cart button in the other selector.
There are two possible ways to achieve what you describe. Either you will need to develop two custom controls, one for listing and one for adding to shopping cart. And save values from first selector so that they can be read in the second selector. For example in session variable.