mergeDuplicates="true" did not work well in MultiSelect mode - sapui5

Question

I want to achieve mergeDuplicates in Multi Select table, just like guideline said:
But in my DEMO, there is still border-top in my checkbox, what should I do? I don't want to overwrite UI5 CSS.
<Table
id="table"
mode="MultiSelect"
growingScrollToLoad="true">
<columns>
<Column mergeDuplicates="true"><Text text="column1"/></Column>
<Column><Text text="column2"/></Column>
<Column><Text text="column3"/></Column>
</columns>
</Table>

Answer 1

IMHO, the concept of mergeDuplicates is bound to the cell content and therefore doesn't extend to the selector cell. But obviously, the guideline and the control concept then don't fully match.
I would suggest to slightly modify Ash Kander's proposal. As the table might render individual ColumnListItems individually and at different points in time, attaching to the onAfterRendering of the table won't help.
Instead, attach to the onAfterRendering of the items by using a delegate. To make this fully work, you have to do this early enough on the template for the items, before data binding starts cloning that template.
In your DEMO, this is easily possible in onInit before you create and attach the model (I gave the template the id "cli"):
this.byId("cli").addEventDelegate({
onAfterRendering: function(e) {
var $dom = e.srcControl.$();
if ( $dom.has(".sapMListTblCellDup") ) {
$dom.find("td.sapMListTblSelCol").css("border-topcolor",
"transparent");
}
}
});
See http://plnkr.co/edit/eNb83KvF1BpAp5eGSpOS?p=preview .

Answer 2

Seems like a bug in the table renderer. No way you can address it NOW without touching the CSS.
This will work, but this overrides the css (in your controller):
onAfterRendering: function() {
$('.sapMListTblSelCol').each(function(index, col) {
if ($(col).next().hasClass('sapMListTblCellDup')) {
$(col).css('border-top-color', 'transparent')
}
});
},