Do some Pokemon have a higher chance of having one ability over another?

Question

Excluding dream world abilities.

Answer 1

Some species of Pokémon may have multiple Abilities. Pokémon caught in the wild will have one of two possible Abilities, and there is a 50% chance of encountering either. In terms of game data, these Abilites may be thought of as being stored in separate slots (i.e. Munna has Forewarn in the first slot and Synchronize in the second).

Source: http://bulbapedia.bulbagarden.net/wiki/Ability

Answer 2

No its a 50-50 chance always