Both were manufactured by IK or Ikarbus in Serbian territory. Not surprising only about 12 of each
were delivered to combat units of the Yugoslav Royal Air Force.
IK-2 was indeed manufactured by Ikarus (no 'b') while IK-3 was not, it was the responsibility of Rogozarski.
The IK in the designation comes from the initials of the designers - Ljubomir
Ilic and
Kosta Sivcev, it has nothing to do with the company that manufactured the planes.
Yugoslavia had quite a capable aeronautical industry producing hundreds of modern planes however the decision was made to focus on building proven foreign designs under license - Hurricanes, Blenheims, Do-17's and others. There have been good reasons why only 12 of each IK's have been delivered.
IK-2 had a very protracted development starting with the IK-L1 prototype, which caused it to be pretty much obsolete as soon as the first pre-series of 12 was deployed, that's why there have been no more produced.
IK-3 also had its fair share of problems (crash of the first prototype which delayed the production of the pre-series again of 12) but it was ordered into full scale production. One of the pre-series machines (No.7) has been modified to serve as pattern for the full series production with some aerodynamic improvements, reactive exhaust, some simplifications for easier manufacture etc, and this has been delivered to operational units just as the German invasion started. 24 airframes in various stages of completion have been at the factory when Yugoslavia surrendered.
A prototype for a twin-engined heavy fighter IK-5 was also under construction, but this came to nothing due to war.
There was also a project underway to undertake a series production of a DB-engined Hurricane version named LVT-1. This was built and undergoing teste only to be lost in action when war broke out.
Several other interesting projects have been underway - Ikarus B-4 a locally designed update for Blenheim I in the similar fashion to Blenheim IV but created without any help or documentation from the British (the prototype later ended up in Finland with other Blenheims Germans captured), Ikarus Orkan fast recce-bomber, Rogozarski R-313 "destroyer", and Zmaj R-1 bomber - all undergoing prototype testing.