ActionListener running without action

I have 2 Jcomboboxes(drop down list) with checkboxes. So user can select multiple items using drop down list. I can select one or multiple items from first combo box.It is working nicely. Then I select one or multiple items from second combo box.It is also working nicely. Then if I again select item from first combo box then actionlistener running two times.First time running according to user action. but second time without user action.Why this happen? I used separate names and separate actionlisteners for each combobox.Thanks for any help.

            ActionListener a0 = new ActionListener() {
                public void actionPerformed(ActionEvent event) {

                    CellItem item = (CellItem) table.getValueAt(row, 0);
                    CheckComboStore store = (CheckComboStore) categoryComboBox0
                            .getSelectedItem();
                    CheckComboRenderer ccr = (CheckComboRenderer1) categoryComboBox0
                            .getRenderer();
                    ccr.checkBox.setSelected((store.state = !store.state));
                    if (store.state) {
                        arrlist0.add(store.id);
                        reflist0.add(store.ref);

                    } else {
                        if (reflist0.contains(store.ref)) {
                            arrlist0.remove(store.id);
                        }
                    }

                    item.setReferenceObject(arrlist0);

                    table.setValueAt(item, row, 0);
                    table.setValueAt(new CellItem(categoryComboBox0), row,
                            column);

                }
            };
            categoryComboBox0.addActionListener(a0);

            setComponent(categoryComboBox0);

            return categoryComboBox0;
        }

I got help this http://ift.tt/1xiHjf4 url to create dropdown list with checkboxes. I added user entered items (id),status(true or false) and reference (1,2,3,4) into arraylists.If user unchecked once checked values then I removed that item from the list checking its reference.