" 4. The grade point average will include all attempts at a given course that result in a grade of A+, A, A-, B+, B, B-, C+, C, C-, D+, D, D-, or F. However, to help freshmen and transfer students adjust to the University of Maryland, College Park, the following two exceptions allow for the cumulative GPA to be calculated so that only the higher grade is included:
a. When the repeated course was taken within the students first semester at University of Maryland, College Park, or
b. When the repeated course was taken within the students first 24 credit hours attempted (including transfer credits) or within the semester during which the student reached the 24th credit hour attempted. "
University of Maryland Undergraduate Catalog 2007-2008
Under "Campus Repeat Policy", about a fifth of the way down the page.
I think the "First semester" part A is for students who transfer in with above 24 credits, and part B applies to freshmen.