Buying a Tandem Double Buggy
If you have twins or children very close in age, a tandem double buggie is a great 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 rocky terrain.
Many transform into travel systems that take 2 carrycots or car seats. However, they can be heavier and longer than single pushchairs and might feel less stable when as they bump up the kerbs.
Convertible
If you're looking for convertible stroller that converts from single to double or to add a second seat to an existing one, there are many options to choose from. The Vista V2 from UPPAbaby is big, beautiful stroller that converts easily from a single to a double by adding the rumble seat (available separately). It is more expensive and less maneuverable because the second seat is positioned in front of the first seat. Nuna Demi Grow provides a similar choice however, it doesn't have storage under the seat when used as a double stroller.
Other options include all-terrain twin buggies as well as fixed-wheel joggers that can accommodate two children. They are generally more expensive, however they're designed to last longer on rough terrain and can have a higher resale value.

Independent seat recline
If you want a double stroller that will accommodate children of different ages, you will need one with an independent recliner for both seats. This will allow your older child to relax while the baby is in a bassinet and the reverse is true.
Take into consideration the size of your pushchair and consider the ease of you to maneuver through doors and on public transportation. If you have extremely narrow doors, it may be a good idea to consider a side-byside pushchair like the Mountain Buggy Duet which has the advantage of having a footprint that is similar to a single buggy however, it is able to accommodate two seats and car seat adaptors.
Tandem buggies generally are smaller than side-byside models, and aren't as difficult to maneuver around kerbs however, they can accommodate a bigger range of seat/carrycot/car seat combinations making them a good option for twins or siblings of different age. They are also more expensive than single-to-double buggies but are a worthwhile purchase if you plan to keep it for a long time and will retain a decent amount of resale value should you decide to sell it after your children have grown out of it.
This feature will allow you to place your child in the most comfortable position for naps or to observe. This is essential when your child is in the back seat and wishes to nap while the older child prefers to sit and observe the surroundings.
A few brands have an exclusive seat design that allows the back seat to fully recline to an almost flat position which is perfect for infants. The iCandy Orange, for example, has stadium-style seating that can be reclined in multiple positions. It also comes with a UPF 50+ canopy and peekaboo windows.
Larger than twin buggies
They are perfect for siblings with different age groups, and you can move about without worrying about your children touching. They're usually a more spacious, with one seat behind the other. The seats can be reclined fully for infants, or put in an upright position for toddlers.
A popular choice is the Mountain Buggy Duet, which is the tiniest side-by-side model available and features an identical footprint to a single buggy. It also features an adjustable handle, making it easy for parents of different heights to push as well as a handbrake, which is useful when tackling difficult hills. It is suitable for use from birth, and can be used with a wide range of car seats and carrycots.
The iCandy Wave is another option. It can be folded in duo or mono mode in a single click. The frame's clever design can be expanded to accommodate a second seat and can be used with up to two carrycots or car seats making it a great option for older siblings that wish to sit together and share the view. It's a little longer than other models but still feels easy to steer and has soft suspension to tackle the kerbs.
There are plenty of 3-wheeler tandems with inline tires that offer stability and swift steering. Take a look at Phil and Teds inline models as well as iCandy Peach and Pear buggies. They are often folded into the size of a single buggy, which is helpful if you struggle with storage at home or need to lug it in and out of the car on public transportation.
Be aware that a two-wheeled buggy will be more heavy and heavier than a single compact buggy. Make sure you know what you want prior to making a purchase. You'll need to take it off and on subways, trains and buses regularly so it needs to be easy to operate and manage. You might need to manage the car seat when you take your child to school or the nursery.
From your birth, you are a good candidate
If you're expecting twins, or have a second child after your first, you're going to need to find a pushchair that fits the entire family. Double buggies tend to be heavier and bulkier, as well as more expensive than single strollers. However they are much more maneuverable in tighter doorways and around obstacles such as curbs. Many double buggies can be used with piggyback boards (available from the manufacturer or as an add-on). This lets you transport three children at the same time.
Tandem pushchairs place one child ahead of the other. They're a good choice if your children are similar in age and get along well. However, they're not 100% secure Side-by-side chairs could kick or punch one another, and children with different heights may argue over who should sit higher. A tandem high-low model is able to solve this problem by elevating the seat towards the rear, preventing your child's older one from sitting 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 accommodate both the newborn and the older child. It has a clever frame that expands in width when you add the second seat. It folds flat to make it a compact storage. double pushchair padded straps, buckles, and seats are all of the best quality we have encountered in any of our tests. The seats can be reclined independently and the canopies are big and spacious with UPF 50+ protection and peekaboo windows.
The only downside to the iCandy tandem is that it is a bit expensive. But a high-quality tandem will last you for a long time and will have the highest resale value, so at the end of the day you'll likely recover a portion of the cost. It doesn't have the same variety of seating configurations that others of our top choices however the iCandy is a good choice for families that don't want to spend a lot.