Why do some fighters have two engines?
Taking the Sukhoi Su-35 for example, it has two engines, each capable of producing 86.3 kN of dry thrust, combined they produce 172.6 kN. With afterburner they produce 284 kN (142 kN each).

The jet engine on the American F-22 produces 156 kN with afterburner, close to the 142 kN of the Su-35.

Soviet Union / Russia made the Kuznetsov NK-32 military jet engine, capable of 137 kN (dry) and 245 kN (wet).

So, the ability or technology to make a powerful jet engine is not the reason. It's just powerful engines are much bigger.

The main reasons for selecting a twin engine design are:


Slimmer design, two smaller engines make for a slimmer profile than one big engine.
Redundancy, in case one fails, especially important for big fighters.
Afterburners are easier to make for smaller diameter engines.