Buying a Tandem Double Buggy
If you have twins or children very close in age, a tandem double buggie is a fantastic option. They're a bit smaller than side-byside buggies and are ideal for maneuvering tight spaces such as entrances, on public transportation and on rough terrain.
Some are able to be converted into travel systems that use two carrycots or child car seats. However, they can be heavier and longer than single pushchairs, and might feel less stable when as they bump up kerbs.
Convertible
If you're looking for convertible stroller that can be converted from a single to a double or to add an additional seat to an existing one, there are several options available. The UPPAbaby Vista V2 is a big, beautiful stroller that easily converts from a single stroller to a double by incorporating the rumble seat (available separately). It is more expensive and less maneuverable due to the fact that the second seat is positioned behind the first seat. Nuna Demi Grow offers a similar option however, it doesn't have storage under the seat when it's used as a double stroller.
double pram and pushchair include twin buggies that have all-terrain wheels and joggers with fixed wheels that can hold two children. They are generally more expensive, however they're designed for long-distance trips over rough terrain and can have a higher resale value.

Independent seat recline
If you're looking for a double buggy that can carry children of different ages, you'll require a model with an recline that is independent for both seats. This allows your child of a higher age to be able to relax while your baby is in the bassinet and vice versa.
Take into consideration the width of your stroller and consider the ease of you to navigate through doors and on public transportation. If your doorways are very narrow, you may want to consider a side-by-side pushchair such as the Mountain Buggy Duet. It has a footprint that is similar to a single stroller but it can accommodate two seats and car seat adaptors.
Tandem buggies are generally a little longer than side-by-side models, and aren't as difficult to maneuver up and down kerbs, but they can accommodate a wider range of seat/carrycot/car seat combinations and are a great option for twins or siblings of various age groups. These buggies are priced higher than single to double buggies, but they're worth the cost if you plan on keeping it for many years. They'll also keep an impressive amount of value when sold once your children are old enough to use the buggie.
This feature allows you to place your child in a comfortable position for naps or to observe. This is especially important if you have a child younger than in the rear seat who will want to lie back and sleep while the more mature child wants to sit and observe their surroundings.
A few brands have a unique design for their seats that allows the back seat to fully recline into a nearly flat position that is perfect for babies. For example the iCandy Orange has raised stadium-style seating and can recline the toddler seat included and the additional RumbleSeat into multiple positions so your kids can have a choice of where they will sit, as well as offering an excellent UPF 50+ canopy with windows that peek out.
Larger than twin buggies
They are ideal for siblings of different age groups, and you can get around without worrying about your children touching. They're typically a bit larger, with one seat sitting behind the other and usually offering a fully-flat recline for infants (or an upright position for toddlers).
A popular choice is the Mountain Buggy Duet, which is the tiniest side-by-side model available and has the same footprint as a single buggy. It has an adjustable handle that makes it easier for parents to push and a handbrake, which can be useful on hills that are steep. It is suitable for use right from birth, and can be used with a range of car seats and carrycots.
Another option is the iCandy Wave, which has the convenience of a single click to fold and can be used in duo or mono mode. The frame's clever design can be expanded to accommodate a second seat and can be used with up to two car seats or carrycots so it's an excellent choice for older siblings who want to sit in a group and share the view. It's a little longer than other models, but it still isn't heavy and has a soft suspension for the kerbs.
There are many 3-wheeler tandems with inline wheels that offer stability and quick steering. Check out Phil and Teds inline models or iCandy Peach and Pear buggies. Often these can be folded down to size one buggy, which is helpful if you struggle with storage at home or frequently need to transport it into and out of the boot on public transport.
Be aware that a double-wide buggy is more heavy and bulkier than one compact buggy. Be sure to know what you want before you buy. It will be used on trains, buses and subways frequently, so it should be easy to operate and use. You may need to juggle the car seat in and out while taking your child to school or to nursery.
From birth
There will be a need for a pushchair for your entire family whether you're expecting twins, or if you have a child after you've had your first. Double buggies are typically larger, heavier and more expensive than single strollers, but they can also be easier to maneuver through narrower doors or around obstacles like curbs. Many double buggies work with piggyback boards (available from the manufacturer or as an add-on). This allows you to carry three children at once.
Tandem pushchairs put one child in the front of the other, so they're usually a better option if you have two kids who are close enough in age to function well. They're not 100% secure. Siblings seated side-by-side may punch or kick each other and children of different heights may fight over who sits taller. A tandem high-low model can solve this issue by elevating the seat to the rear, which prevents your older child from being sat on the bottom and not getting any view.
The iCandy Wave is a good alternative for parents looking for a convertible double buggy that includes a carrycot that can fit both infants and an older child. It features a smart frame that expands widthways when you add the second seat. It folds flat to make it a compact storage. The padded seats are comfortable, the straps are easy to fasten, and the buckles some of the most comfortable we've seen on any of our tests. Both seats can recline independently, and the canopies are big and spacious with UPF 50+ protection as well as windows that can be seen from a distance.
The only downside to the iCandy tandem is that it is a bit expensive. But a high-quality tandem will last you for years and retain the highest resale value, so in the end, you'll likely recoup some of the cost. The iCandy doesn't come with the same seating arrangements as our other top picks. It's nevertheless an ideal choice for families who don't wish to spend lots of money.