When the user clicks on item #2 for the second time it become deselected.
This is when you would remove it from the 2nd listbox. Try changing the
multiselect property of the listbox so the user can select (highlight) more
than one item. If you want to remove the items from the 1st listbox and
add them to the 2nd listbox as suggested by Colin this should be done in
the double click event of the listbox or use a command button to move all
selected items at one time.

Hope this helps!

"eddie" <ez1115@yahoo.com> wrote:
>Michelle wrote:
>>"eddie" <ez1115@yahoo.com> wrote:

>Hi, Michelle!
>What about if the user choose items 1, 2, 3 from listbox1 in the said sequence
>and add them to listbox2
>and then come back to the listbox1 and choose item2 again?
>>>Suppose I have two listboxes. This first listbox is populated with a list
>>>of data and the second listbox is empty.
>>>I want the user to be able to choose any of the items from the first listbox
>>>and copy it to the second listbox.
>>>But if the selected item from the first listbox is already in the second
>>>listbox, the copy won't happen. This means
>>>no duplicate items are allowed in either listboxes. How can I do this?

>>If you fill the 1st list box with unique data and you are only filling

>>2nd list box via the 1st list box you will not have any duplicates. Just
>>make sure if the user deselects an item in the 1st list box you remove

>>from the 2nd list box.