No, if you are about the post the same (or very similar) information, the way you "add confirmation" is by up-voting the original post.
Each question is meant to be the canonical source of whatever information is being asked, but not everyone is brilliant or insightful always. Multiple answers are encouraged because the first post isn't necessarily the top information available on the subject. If you can clarify an existing post, edit it to add that information; if you have a better answer yourself, post a new answer.
The purpose of voting is to help assure the best answer rises to the top. You don't want to have a lot of redundant reading to confirm the information or arrive at the correct information. That is the assurance and vetting Stack Exchange was meant to provide.