There is no right or wrong on this subject. I will be happy to provide options that I believe will be the best bang for your buck (e.g. I will explain why you do not necessarily need 2 photographers for the entire day. Partial coverage for the 2nd shooter sometimes is preferred by our clients). However, if you do consider having a second photographer, I kindly suggest reading this very insightful article about 2nd photographer: click here.
Not related to this post; this is simply a photo of the grand stairways at Oxford University that I took in spring 2015 that were also used for Harry Potter movies. I am an HP and Oxford fan! :)