Devices generate events, and those events have attributes. For example, a multi-sensor may generate a contact.open event or an acceleration.active event (and many others). These are distinct events, and in the case of Tony's rule, either will trigger the rule. Notice that the rule display says this event OR this other event. The issue that arises is that opening the door will cause both of those events to happen, and consequently the rule will be triggered twice. In the case of Tony's rule, this is ok and works as expected, and is the reason he put the delays in the rule. It is non-deterministic which of those two events will trigger first, and the rule has to work for either order.
I'm not sure what grouping of triggers would mean. The device is still going to throw those events; the app is still going to have subscriptions to them. In Tony's case it needs both events and both subscriptions so that it can distinguish between the door opening, closing, or being knocked on.