I'm not too familiar with drill downs, but this is what I remember.
you have a report, you click on something, a new tab opens with that item's information.
since you item in on a subreport, I am guessing that the first repeat is CR opening the subreport (you drilled down from the main report). If this is the case, I don't think that there is a way to get rid of the duplication.
the 'obvious' answer, though probably more difficult is to get rid of the subreport. The only way (typically) is to get your data from a stored procedure, creating the data that would be in your subreport.
Now that you have all the data that you need in one line the report changes to have at least 1 more group on it and your detail becomes the subreport data...at least that is what I typically do. Reduces the number of hits to the database, but can make for a simpler/more complex report (depends on how you view it)
HTH