Backup name

Mrs.S • Wife, mother, writer... ❤️ a good debate 🗣 Living in the Land of the Free 🇺🇸
For those of you who have decided what you're going to name your baby, do you also have a second name in mind? I've heard that it's not a bad idea in case the name you've chosen just doesn't "fit" when you see your little one for the first time. My husband and I know what we're going to name our son, but we haven't discussed an alternative yet. I think it's a good idea, but we had so much trouble agreeing on the name we've chosen that having to agree on another one doesn't sound too appealing. 
Do you have a backup name? Thoughts?