One of the classic questions I seem to always get asked is do I need a second photographer for my wedding? Unfortunately there is not always a straight answer on this but hopefully I can give you more clarity because probably 99% of my weddings I personally do not have one.
1. MORE PHOTOS
Usually the first reason a couple would want a 2nd photographer is because they will get more photos. But in reality that's not the case. You may get more variety in your photos but I find even when I solo shoot a wedding there is a lot of variety I am able to deliver. Focus on the quality rather than quantity.
2. MUST HAVE SHOTS
I know it seems like a no brainer but sometimes it is overlooked. Usually the average coverage time for a wedding is eight hours. I personally deliver about 500-600 photos based on eight hours of coverage. However, if you are thinking you both may want more photos than that make sure your photographer knows this up front. Some photographers will charge extra for high res deliveries. Make sure this is clarified before booking.
3. TWO PLACES AT ONCE

One instance where I would say its a must to have a second shooter is if the bride getting ready location and groom getting ready location are really far apart. In this case it would make sense to have a second photographer. One added bonus is during the wedding party photos it moves a lot faster because the groom side and bride side can be photographed at the same time. At the end of the day it just leaves you more time to party with your guests
4. THE DETAILS

You have been planning out some of the details for months possibly even a year and we know you want them captured in their best way. If your photographer is not able to allot enough time before the ceremony to capture all these details. You may want to look at bringing on a second shooter so maybe while family pictures are being taken the second photographer can capture all the detail shots.
Honestly there are certainly some pros to having a 2nd photographer. For me personally in most cases I do not have a 2nd photographer. The main reason is I allocate more time during the getting ready part of the day to make sure I can capture everything appropriately and you both do not feel rushed. The only time I will elect to have one's if your getting ready locations are really far apart. At the end of the day this is YOUR wedding. So if in your gut you think you want a second, freaking do it!