I think having up/downvotes AND likes is overkill. You&users should fokus on one.
As reddits vote system is far better than the simple likes of facebook, I think you use that and just get rid of the likes.
I think I agree with this, will try to notice more as I use the platform.
To keep likes for the ones used to it, you might consider to redesign the up/down arrows to a heart for upvote=like and a ... x-ed heart or a skull or whatever for dislike. No dupliicates, redditors&facebookers happy