Yes you over-pitched. Result is yeast will not reproduce as much as it would have if you had pitched the right amount, so the beer will be made with 'old' yeast rather than new yeast.
What is going to happen .... probably nothing that you will be able to detect. Fermentation may end up a point higher than it otherwise would have, but you will never know. The yeast may not create all the esters that it would have done normally, but it is SO-5, a clean yeast, so that doesn't matter. There may be other issues with over-pitching, but I've not heard of any real issues being reported, and many people have pitched on whole cakes with no issues.