Probably because the second tower was hit lower, and thus the weakened section had far more weight to support.
andruejaysin Reviewed by andruejaysin on . How they fell Here is some information on the WTC. from 3rd party...ill link ya http://www.civil.usyd.edu.au/wtc.shtml World Trade Center - Some Engineering Aspects Height: 1,368 and 1,362 feet (417 and 415 meters) Owners: Port Authority of New York and New Jersey. (99 year leased signed in April 2001 to groups including Westfield America and Silverstein Properties) Architect: Minoru Yamasaki, Emery Roth and Sons consulting Rating: 5