How to allow dublicated items in select?

I use select with created items. When I hit ENTER key on select ,the item is added to select, the problem is when I add the same element., select remove it , But I want to have another behavior, If I type the same element => the element is not removed from added items and elements with same name are removed(only remove dublicates)

Two variants are possible for me:
1. Type element with the same name -> both are saved in list(select should not remove any of dublicate items)
2. Remove only dublicate items(type element name => it is added => type the element with the same name -> remove only dublicate)

**Is it posssible to do that?**

**If no so how can I get the dublicated item from select that was removed?**