My apologies. I submitted, but when it has been submitted before it usually just redirects you to the previously submitted one. Not sure why it didn't do this for me this time!

EDIT: Seems to be "http" vs. "https".

No need to apologise. If something is missed the first time, people see it the second time and it gets voted up to the front page then people want to see it. With the voting system if it truly is a "dupe" it wont get voted up...