Do any parents of two little ones have advice about the single vs. double stroller situation? Our second baby is due at the end of this year and our toddler will be 18 months at that point- so we will definitely need a double stroller. I'm just not sure if we should keep her single one or sell it. I don't like hanging onto things that aren't going to be useful in the future and it's in great condition so I'd like to pass it on if it's not likely we will use it. Has anyone else used the single later on when your first was a bit older and the second still needed a stroller? Is it worth taking up storage space?