I saw several posters talking about having a 2nd bike as a backup in case the first isn't available. So my question is how often did that really happen?

I have two bikes but one was given to me as a gift at the same time I bought a used bike. The gift bike was brand new but isn't a necessary better bike. I split time between the two for commuting and weekend ride but it seems I don't really need two road bikes and I'm considering selling one, probably the gift one.