Hello. I need to know how to write some code that will identify rooms that
are scheduled to be used at the same time. See my source data below:

ColA ColB ColC ColD ColE ColF ColG
RMP Period Term Code Sec course Tchr
A4 1 HS1 HSCT100 1 Basic Bus Apps Adolfs, Patricia
A4 1 HS2 HSCT100 6 Basic Bus Apps Adolfs, Patricia
Gym 1 HS1 HSPE200 2 Team Sports I Deutsch, Steven
B10 1 HS2 HSSS211 10 Civics Clifton, Philip
B12 1 HS1 HSSS110 2 US History S1 Thompson, Kourtney
B12 1 HS1 HSSS316 1 Modern World Unknown 3
B12 1 HS2 HSSS111 2 US History S2 Thompson, Kourtney
B12 1 HS2 HSSS316 6 Modern World Unknown 3

So I have about 3000 records. See room B12 above, this is a double booked
room as in both Semester 1 and 2 Period one has two classes sceduled to meet
in B12. I would like to be able to run code that would strip out all the
duplicate rooms from the non-duplicate rooms based on Semester and Period;
each room can only be scheduled once per term. Any assistance is "way"
appreciated.