Yes, you can. They have to be the same brand and similar (not necessarily identical) locks. You have to get them from a lock service centre, not a DIY shop.
I've had my Chubb back doors (3 of them) suited to the same key. 1 x 3K74 and 2 x 3G114. The main back door is a sash lock (has a handle/latch). Front doors usually are deadlocks without a latch. This is a typical good quality lock, if you have a bit of cash to spare you can buy much more expensive or suited locks. Get all the spare keys you want done at the same time. You may be able to negotiate a discount on spare keys. If you lose a key you can get the agent to supply or fit new sets of levers and keys instead of buying whole new locks.
Be sure to get BS 3621-2004 locks with the latest larger 20mm bolt throw. If you buy an own-brand lock and it has the BS it will probably be almost as good as a major brand. The Chubbs now have a 15-year guarantee and I have some older than that. Cheaper brands sometimes suffer from internal rust or broken springs.
Sometimes you can get a Legge or a Yale pair of locks, suited, in a DIY shed, in a pre-pack.
It is also possible sometimes to buy sets of levers or detainers with keys to suit if you like tinkering.
If you like Eurocylinder locks (I don't) you can buy sets of cylinders e.g. from
Screwfix and swap them yourself.
It is usual to have some kind of self-latching rimlock on the front door as well as the mortice lock, and rack bolts top and bottom on the back door, for increased burglar resistance. You can get self-latching deadlocking mortice locks but they are very expensive.
