The two seats fighters or in general attack aircraft are very rare. Usually, the modern aircraft of this kind have only one pilot that flies the aircraft and at the same time uses the guns too. The aircraft with the two seats side-by-side is even rarer. Let's see which these really interesting aircraft are!
F-111 Aardvark
The most known of its kind, the American F-111 Aardvark, was designed as a long-range interception aircraft. Due to its scale, the F-111 is not so maneuverable, so its role changed to bomber and reconnaissance.
Hawker Hunter
The British Cold War jet was designed with a side-by-side two-seat operational configuration. The Hunter works as a training and observation aircraft.
Su-34
One of the most modern aircraft on the list, the Russian Su-34 has impressive maneuverability.
Su-24
One more Russian, the Su-24, has as a main target land unit.
Some other, non-fighters aircraft with a similar design are the Grumman A-6 Intruder, the Douglas F3D Skyknight, the Northrop Grumman EA-6B Prowler, the Sea Vixen, and more.
Let us add that the specific design is quite useful in training aircraft. Because the two pilots are side-by-side, it's easier for the student to be examined and taught. Think of it as driving less... just a 'bit' more difficult!