Case Merge Premium includes the Subject Conversation field, which trims out extraneous text from an email subject line in order to yield more precise results when detecting duplicates.
When searching for duplicate cases, the Subject field on the case may include extraneous information from an email subject line. For example, the email subject may contain "FW:" or "[Email Loop Protection]" which are certainly not unique to a single issue or case.
Case Merge Premium includes the Subject Conversation field, trimming out the following text from the original subject line of the email.
We recommend using the Subject Conversation field in your duplicate criteria for more precise results when detecting duplicates with Case Merge Premium. For information regarding configuring duplicate criteria, please refer to the Case Merge Premium documentation.