At the beginning of the war, Croatia’s early military forces had a limited supply of the M70 rifle so it was normal for a soldier to have to buy his own rifle and accessories. Many were purchased on the black market and from other sources resulting in AK rifles and accessories from many counties with most of them coming from Romania.
Later on Croatia began to purchase Bulgarian as well as Russian rifles and accessories from Lithuania. He noted that is why most of the Russian and Bulgarian bayonets in Croatia have been re-stamped with four digit serial numbers on them.
After the war there was a deficit of bayonets since the soldiers did not have to return them with their rifle. This resulted in Croatia ordering bayonets and some other accessories for their AK rifles from the Maadi factory. He noted that he has never seen the dark blue Maadi bayonets anywhere outside Croatia and that this color was the most commonly imported, but they also sent some older supplies of brown and black bayonets.
All M70 bayonets that you may find in Croatia were produced before 1991, so they would be considered Yugoslavian bayonets and there is no difference between pre and post 1991 models besides the name of country.
Information courtesy of Mislav (aka Croblade)