Philadelphia Free Press was a 1960s era underground newspaper published biweekly in Philadelphia, Pennsylvania from 1968 to 1972. Originally launched at Temple University in May 1968 as the monthly "Temple Free Press", it separated from Temple and became the "Philadelphia Free Press" in September 1968.
The Philadelphia Free Press was published once every two weeks
Biweekly means every two weeks. I think the system got it wrong because I used phrasing not found in the context