ComboboxItem hilites drop-down records

[curiousgally]

ComboboxItem hilites multiple records as shown in the attached screenshot.
Can someone explain this behavior and how to control it.

I'm trying to achieve custom behavior for comboboxitem:

        DataSource supplyItemDS = DataSource.getDataSource("employees");
        final ComboBoxItem filteredSelect = new ComboBoxItem("filteredSelect");

        final ListGrid pickListProperties = new ListGrid();
        ListGridField name = new ListGridField("Name");
        ListGridField eId = new ListGridField("Email");
        pickListProperties.setDataPageSize(20);
        filteredSelect.setPickListBaseStyle("myBoxedGridCell");
        filteredSelect.setSortField(1);
        pickListProperties.addRecordClickHandler(new RecordClickHandler() {
            @Override
            public void onRecordClick(RecordClickEvent recordClickEvent) {
                Record rec = recordClickEvent.getRecord();
                String value = filteredSelect.getEnteredValue().contains(",") ? filteredSelect.getEnteredValue().substring(0, filteredSelect.getEnteredValue().lastIndexOf(",") + 1).trim() : "";
                filteredSelect.setValue(value + rec.getAttribute("Name") +",");

            }
        });

        filteredSelect.setTitle("Item (Select)");
        filteredSelect.setOptionDataSource(supplyItemDS);
        filteredSelect.setDisplayField("Name");
        filteredSelect.setValueField("Email");
        filteredSelect.setPickListWidth(300);
        filteredSelect.setPickListFields(name, eId);
        filteredSelect.setPickListProperties(pickListProperties);
        filteredSelect.setShowPickerIcon(false);
        filteredSelect.setPickListFilterCriteriaFunction(new FormItemCriteriaFunction() {
            @Override
            public Criteria getCriteria(FormItemFunctionContext formItemFunctionContext) {
                String searchText = filteredSelect.getEnteredValue();
                String scz = searchText.contains(",") ? searchText.substring(searchText.lastIndexOf(",") + 1).trim() : searchText;
                AdvancedCriteria criteria = new AdvancedCriteria(OperatorId.OR, new Criterion[]{
                        new Criterion("Name", OperatorId.ICONTAINS, scz),
                        new Criterion("Email", OperatorId.ICONTAINS, scz)
                });

                return criteria;  //To change body of implemented methods use File | Settings | File Templates.
            }
        });

Also i need to show the data that starts with the text typed into the textitem and then the data that contains. Any ideas to achieve this.

Thanks.

[Isomorphic]

Your dataset may have colliding values for the primaryKey or the valueField set on the ComboBox.