If this is in the Month view, the widget normally adds the start time before the title, like 0:00A or 4:00P, although the format may be different depending on your language. In the week view you should get both the start and end dates added.
I have the same problem, but I am not interesting in the 'Why', I just want to remove it, and show the name of my entity I ca not remove the start or end date in the widget options, but the start and end are the same (due date, which is only 1 date). (i am using version 7.12)