Calendar sort order in Week view

My Calendar application has events of two different types which often start and end at the same times. When displayed in the Week view, I would like to be able to specify the display order so that events of each type are consistently displayed in the same order on each day.

As it is, sometimes type 1 events are displayed in the first column and type 2 in the second; sometimes the other way around. The inconsistency makes the calendar difficult to read and I haven’t been able to determine what, if anything, controls the sort order.

Any help or suggestions would be greatly appreciated!