I've noticed that a few words may be both a noun and an adjective, remain spelt the same, but change the pronunciation of -ate to ət or āt. Sometimes the meanings are related, others they are not.
For example: separate.
We separate the objects into separate categories.
We pronounce the first with āt but the second as ət.
Off the top of my head, the only other I can think of is "conjugate", though I'm fairly certain there are others that are just not coming to my mind at the moment.
Is this just coincidence or the product of some understandable process?