Some claims that appear to be duplicates are actually claims or claim lines that contain an item or service, or multiple instances of an item or service, for which Medicare payment may be made. Correct coding rules applicable to all billers of health care claims encourage the appropriate use of condition codes or modifiers to identify claims that may appear to be duplicates, but are in fact, not.
For example, there are some Healthcare Common Procedure Coding System (HCPCS) modifiers that are appropriate to be appended to some services and can indicate that a claim line is not a duplicate of a previous line on the claim. Level I modifiers would typically be used by a biller to indicate that a potential duplicate claim or claim line is not, in fact, a duplicate. Level II modifiers may also be used. The Level II modifiers “RT” and “LT,” for example, indicate that a service was performed on the right and left side of the body, respectively.
However, not every HCPCS code has an appropriate modifier to indicate that a claim line is not a duplicate. In that case, the claims and claim lines are reviewed by Medicare Contactors’ local software modules for a determination, or they suspend for contractor review.
To know more on how to identify the Exact Duplicates please check http://www.cms.gov/Outreach-and-Education/Medicare-Learning-Network-MLN/MLNMattersArticles/Downloads/MM8121.pdf