Just something to think about...
Given that it appears that you can have multiple lines for the same Claim # and Date (not sure if these are different line items for a particular invoice or what), are you saying that it is not possible to have two distinct line items that just happened to be the same dollar amount (and hence, should really be counted separately, even though they may be the same amount)?
Don't know if that is possible, as we really do not know the background on this.
But just something to think about, in case those three fields are really not enough to determine what is a duplicate and what is not.