Requester Table Indexes

For the Requester table I notice the indexes are based on the fields of Company, Requester and Req_Location. In the system we have the some duplicate records. Here is my question if the data is the same on the records how are they uniquely identified? Does the upper or lower case make a difference? I would not thing that it would. Below is an example of one of the duplicate records:

Company  Requester  R_Name  Approve_CD  REQ_Location  Active_Status etc.

1000           HHC51       HANDHELD HILLCREST  MMHHI   space   A

1000            hhc51         handheld hillcrest              MMHHI    space   A

The remaining fields are the same.

Any ideas?