Since this is the OOTB feature of the Sitecore so I will not recommend changing in it but if you just want to update the UI of the multilist with search
field so that content author not see the template name then you can simply update the BucketList.js
file located in \sitecore\shell\Controls\BucketList
under your website. In this file you need to update the constructor for request success handler, see the commented line in below code -
self.SuccessHandler = function (multilist) {
return function (request) {
var response = eval(request.responseText);
multilist.options.length = 0;
multilist.removeClassName('loadingItems');
var itemIdsHash = {};
var reducedItems = [];
var i;
var item;
for (i = 0; i < response.items.length; i++) {
item = response.items[i];
if (!itemIdsHash[item.ItemId]) {
itemIdsHash[item.ItemId] = true;
reducedItems[reducedItems.length] = item;
}
}
for (i = 0; i < reducedItems.length; i++) {
item = reducedItems[i];
//multilist.options[multilist.options.length] = new Option((item.DisplayName || item.Name) + ' (' + item.TemplateName + (item.Bucket && (' - ' + item.Bucket)) + ')', item.ItemId);
multilist.options[multilist.options.length] = new Option((item.DisplayName || item.Name), item.ItemId);
}
self.pageNumber = response.PageNumbers;
self.currentPage = response.CurrentPage;
$('pageNumber' + self.clientId).innerHTML = self.format(self.of, self.currentPage, self.pageNumber);
};
};
You just need to remove + ' (' + item.TemplateName + (item.Bucket && (' - ' + item.Bucket)) + ')'
line.