Dvojak families are Croats and they are mostly from Slatina area. In the past century, relatively most of Croatian residents bearing this family name were born in Slatina area and in Virovitica.
Prevalence
About 90 people with faimily name Dvojak live in Croatia today, in 40 households. There were 60 of them in the middle of the past century, and their number increased by 50 percent. They are located in 6 Croatian counties, in 7 cities and 6 other places, mostly in Slatina (40), Zagreb (10), Virovitica (<10), Vaska in Slatina area (<10), and in Osijek (<10).
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 2007 in source Encyclopaedia of Croatian Surnames.