What are the ages and weights of your children? Some double strollers have seats that recline fully for newborns; others can only accommodate children from the age of 3 or 6 months. Side-by-side double strollers are best for twins or children of roughly equal weight. Tandem strollers and convertibles may be better for children of different ages and sizes. Check to see how much weight each seat holds and how much leg and headroom they allow for growing children.
What are your car seat transport needs? If you need your double stroller to be a complete travel system for two children, choose one that can accommodate two car seats or bassinets. Umbrella strollers typically aren't able to accommodate car seats at all, while jogging strollers may only be able to accommodate one car seat with an adapter. Your best bet may be a simple double car seat stroller frame until your babies are bigger.
How and where you will use it? If you need a double stroller for long, tiring outings, you may want to look at strollers with two equal-size seats. If it's only for outings to the zoo, museum or park where the kids are in and out, a detachable seat or standing ride-on board may work best, especially if one child is much older and capable of doing more walking.
How strong are you? Double strollers can be very heavy. Even the lightest double umbrella strollers still weigh more than 20 pounds, while some double jogging strollers close in on 40 pounds. Whether you live in the city or suburbs, you're going to need to lift the stroller and carry it -- into trunks, up the stairs or onto public transportation.
What is the size of your trunk or car? Most double strollers take up their fair share of space, even when folded. Closely examine the manufacturer's specifications and measure your trunk before buying -- some double strollers are difficult to fit in compact cars. Bulky jogging strollers often have removable wheels so they'll fit in tighter spaces than they otherwise would.
Strollers are a frequently-recalled item due to various safety issues. The most recent recall, in February 2017, involved more than 700,000 Britax and BOB strollers due to a fall hazard when using the stroller as a travel system. The issue is the "Click and Go" receiver mounts that attach the car seat to the stroller; they can fail and cause the car seat to disengage. Consumers should immediately stop using the stroller/car seat as a travel system, although both can be used separately. If you already own a Britax or BOB stroller, you can see if your model is affected here. If you are thinking of buying a used stroller, be sure it has not been subjected to a recall, either this one or in a past recall. You can find that information at CSPC.gov.