A fire broke out around midnight Friday on the unit block of Branch Street in Medford.
Police said two people were injured. They were being treated for smoke inhalation.
The cause of the fire has not been determined.
Crews in Wrightstown battled similar circumstances around 1 a.m. Thursday.
Fire officials at both scenes said hoarding inside the homes hindered firefighting efforts.
Two people were also treated for smoke inhalation in Thursday's fire.