The media said that the second victim was a resident of the city of Masbate, the provincial capital, who died of a heart attack following the quake.
Previous reports indicated that it left one person killed and one injured.
On Tuesday, the United States Geological Survey said that the magnitude 6.6 quake occurred at 00:03 GMT 6.8 miles east of the city of San Pedro.
The province's Cataingan municipality was hit the hardest by the quake. The area suffered quakes up to magnitude 7 and, subsequently, massive damage to residential and office buildings.
A total of 170 people, including 67 in the Cataingan municipality, were wounded as a result of the earthquake, and more than 300 people were forced to leave their homes.
