Whilst browsing the policy list in the Enforce console, you see policies with the same name and policy group. If you enter the policy name in the search field however, only one policy is listed.
Hidden, corrupt characters have been introduced to the policy name during a copy/paste action. Although they are not visible in the console, they cause the policy name to be recognised as unique. This can occur if the policy names are copied out of some third party systems eg. Jira
DLP is a Unicode compliant application however, some character corruption can only be revealed when switching between character encodings
If your policy creation process includes copying/pasting the prospective policy name out of third-party systems, be sure to check and sanitize the text if necessary in Notepad++ first.