DropDown Clear Issue

I have a Collection of Month Objects ( int id, string description ) as data in a dropdown control.
The allowclear is enabled.
When there is no month selected i can see the PlaceHolder description but also de "X" (to clear the selection) that suggest that at least one item is selected. I cannot get rid of it unless i change the id from int to string in the class.
Can you please help me with this?
Thank you!