is it possible to have multiple events in a single area at one time in diablo 3?

According to this source, a map can have multiple events generated. This includes caves, houses, dungeons, and other sub-maps as well. However, there are a limited number of "spaces" (officially called Tiles) within a map where an event can spawn, and there are traditionally more Events than there are tiles for a map. Not every Event available to a map or Act will be able to spawn in one run of that Map. You would need to Leave the game session and start a new one to get different Events to spawn.