Monty and Izzy are nearly two years apasrt, but Teddy is only six months older than Joly. The younger two did play together a lot and it became quite dangerous walking about at mad half hour time,a syou were likely to trip over them. Now they often curl up together, though Joly prefers Monty.
The down side was that being the same sex and age, we had some rivalry. Teddy does still bully Joly, now and then. When Teddy arrived, Joly went back on his toilet trainig.
You never can tell, as some dogs get sick, young, but you could end up with two elderly dogs, needing care at the same time.
Barbara, Monty, Joly and Teddy.