Hashan al-Nutayfat shot dead fellow citizen Mohammed al-Dosari in a dispute, said the statement published by the official SPA news agency.
Another murderer, Mohammed al-Qahtani, was executed after he stabbed a fellow Saudi to death, SPA reported.
The beheadings bring to 65 the number of people executed in Saudi Arabia so far this year, according to an AFP count.
In 2012, the conservative Muslim kingdom carried out 76 executions, according to a tally based on official figures. Human Rights Watch has put the number at 69.