I have 2 males. William is castrated (for medical reasons) and is 7 years old. Louis is entire and 2 and a half years old. They're certainly not best buddies and never cuddle up together or play together, but they tolerate each other well and I don't have any problems with them beyond the occasional bit of grumpy jealousness from Louis if he thinks William is getting too much of my attention. But that's mainly down to me being a one person household at the moment so the dogs have to share me.
I also had 2 entire male Cockers together before my current 2. They occasionally played together but never snuggled up together.
As others have said, I think it's down to the individual temperaments and characters of the dogs. The one thing I've always been warned against is having 2 litter siblings, either both male or both female, as that can cause problems when they reach adolescence and on into adulthood. I knew somebody who had 2 Doberman litter brothers, both nice boys, but one had to be rehomed at about 1 year old because they were fighting so much. I also knew somebody with Labrador litter sisters who were fine together, and someone with Border Collie sisters who fought silently and with purpose and one had to be rehomed.