I've had a lot of people over the years tell me, their chin is 2 years old, they want to find another 2 year old to go with them. This is fine, of course, if they want to match ages, it doesn't matter.... however... the chins don't know they're the same age.
Now, if you pair up a freshly weaned kit with an adult -- yes, they know that they're different ages. But when you're pairing up a 4 month old and a 6 month old, or a 1 year and a 3 year old, or a 2 year old and a 10 year old... they have no idea. It's not quite like people where someone who's 20 can recognize the look of someone who's 60. To chins, an adult is an adult is an adult. You may want to give them an exact-same-age-buddy... but they have no idea whether the buddy you gave them is their age, or could be their grandma's age