Other than the actual training/housebreaking, it is no more daily work for us whatsoever and huge benefits. I have had two dogs (at least... sometimes a couple overlap years of three) for 25 years. Always females, always close in age. My current two play together endlessly and exhaust each other and keep each other company. They are hilarious: chase each other in full-out sprints, wrestle, play tug of war. So much fun.
Only downsides:
*double costs for food, boarding, vet
*harder to "trade" dog care because everyone I know has only one