The most recent fires were reported between 1:34 and 1:43 a.m. Monday.
The first was reported in Benson in the 9300 block of Stricklands Crossroads Road. It started in an abandoned house and no injuries were reported.
The second fire was near Four Oaks in the 1200 block of Stewart Road. No injuries were reported.
Investigators have not said if Monday's fires are connected to a series of fires in the Clayton area that date back to October 31, 2009. According to authorities, the most recent fire in the series of suspicious fires was reported Saturday.
That fire was at an abandoned house on Strickland Road near Swift Creek Road. Callers reported it to 911 around 11 p.m. Saturday. It was the ninth fire in an unoccupied home that investigators say was intentionally set.
Prior to Saturday's incident, Johnston County authorities say eight homes that were abandoned or under construction have been set on fire in the Clayton area since last year.
Saturday's fire was three miles from the Glen Laurel subdivision, where arson is suspected in fires at three homes under construction. Before that, the most recent fire was reported on September 13.
Clayton police and the State Bureau of Investigation are investigating possible links between Saturday's fire and the ones prior to that. So far, todays fires have not been connected to those.
There is a $10,000 reward for information leading to arrests and convictions in the Clayton cases. Anyone with information about the fires should call Clayton police at (919) 553-4611 or Clayton Crime Stoppers at (919) 359-8479.