A second photographer can be a good idea for a few reasons. It gives you great coverage of the groomsmen getting ready (usually the only part the Bride has no knowledge of on the day!) so we can cover more angles during the ceremony (for example, shots of both of your reactions at the start).
It also means that the documentary coverage continues with your guests while I’m taking care of the family group photos and the portraits of just the two of you. Then later in the evening, it’s easier to cover the speakers and guest reaction with two photographers, as well as extended coverage during the dancing.
Having said that, I’m quite happy covering large weddings on my own – I’ve shot French Chateau weddings with 250 guests over 2 days on my own, so it’s not a problem if you decide on only myself.
I work with a number of different second photographers, all of whom are experienced documentary wedding photographers. They all work in the exact same way that I do, so their photos seemlessly fit with my own. Here’s some examples from some recent weddings, all from seconf photographers.