For certain courses (In this case EAS 141, not sure if there are any others) that are only offered for parts of the semester (in this case JANUARY 16 - FEBRUARY 27 or MARCH 6 - APRIL 24) only one of the durations is displayed for all sections.
For example, for EAS 141, it displays all sections of the course under a single heading with the comment COURSE OFFERED MARCH 6 - APRIL 24. So there are 4 courses but two sets of two courses each. The courses in each set appear identical (same time, location, etc) because of this lack of data.
You can see this difference by going to http://skedgeur.com/?q=eas+141 and by searching EAS 141 in spring 2015 at https://cdcs.ur.rochester.edu/