There's a bug in the calendar pop-up if you have events with the same name. From what I can tell, the code looks for a span that contains the name of the event and then applies the pop-up to it which results in the same pop-up being applied to all events with the same name. I'e changed this in my version, so it adds an id to the span with the event id and then the javascript looks for the id with the event id in it
Changes I've mde to get it to work properly:
jquery.calendar.js line 2342
var sp = "<span style=\"cursor: pointer\" id=\"spaneventid_"+e.event[0]+"\">${content}</span>";
views/calendar/tmpl/index.php line 330
DTjQuery('#gridcontainer').find('span#spaneventid_'+v[0]).parent().css('backgroundColor',v[5]).parent().css('backgroundColor',v[5]).parent().css('backgroundColor',v[5])<?php if($calendar_show_popup) { ?>.tooltip({content:function(){
Not sure if this is the best way to do it but it works properly now