BPMN 2.0 allows for multiple end events fired within the same process instance. Attached will be a sample process with an overdue monitoring timer event being fired in parallel to main process flow. A similar pattern is forking a parallel execution without joining the executions later.
In such cases only one of the reached end events will be tracked in ACT_HI_PROCINST - the data model assumes that there is a 1:1 relationship between process instance and end event, while in fact it 1:n. Moreover, it seems to be undeterministic which which end event gets tracked. This is why I regard it as a bug rather than an improvement or feature request.
One possible solutions would be to model an ACT_HI_EXECUTION entity corresponding to the equivalent runtime data model.