Do I accumulate candies from eggs in Pokemon Go?

Yes, we can say multiple.

1. Multiple Candies As have been already commented, candies got from hatched egg is randomly given from 3 up to 35 candies. In your example, you got 22 Dratini Candies, and hatching another might be different.

2. "Rare" pokemons There are pokemons that are spawning rarely in general context. And some of these pokemon that might be rare to you (or not) can be found on the eggs, which differ according to category by miles, 2km, 5km and 10km.

Your total number of Dratini candies will be an accumulation (a sum) of all your Dratini candy rewards.

The number of candies you get from an egg is random (between some limits).

So if you

• get a Dratini (which is one of 17 10km egg Pokémon: ~6% minus an unkown percentage because you can get lower level Pokémon from eggs - see comments - so I'll halve it: ~3%) and
• it will give you 3-35 Dratini candies (it should be random distributed : ~3%,)
• and if you haven't get other candies from catching

than you will have 44 Dratini Candies (at ~0.1%).