The answer is that it is very common.

The award is specifically limited as is lounge / breakfast access.

Anything beyond occupancy of 2 and breakfast for 2 is purely discretionary as a matter of customer service at the property.

Depending on the specific property and the crew on duty, they may not care at check-in and may comp the third breakfast or they may require a second room or impose a charge or anything else (including walking you if they need the room).