Sometimes, parents of a single child decide to get a double baby stroller. The reasons for this are varied; If another baby comes along a year or two after getting the stroller, another one need not be purchased.
In the meantime, the extra seat can be used to take along more gear! 
The space will certainly come in handy. For example, a large bottle of water can be stored on the vacant seat. In other situations, this bottle could hurt the parent’s shoulders and may not fit in the storage compartments offered by the baby stroller.
