Hi @Lachlan and @v-micsh-msft,
Even though Michael is correct there is no Copy option available in Flow at this moment, there are some better options rather than building your flow from scratch for each library. You can submit your Flow as template (when it ran on one of the libraries succesfully at least), though it will than be publicy available as a template (if approved).
A better and quicker option is to Export the Flow to a .ZIP file (I tried it with .ZIP and that worked) and make sure the Import setup option in the Review Package Content section is changed from Update to Create as new. After the export is done, you can go to the MyFlows screen, hit the Import button and select the export file. Make the necessary changes to the import and make it import. Even if the Flow is imported, you can still change the Name and settings. Just change the Name and paths within the Flow to the correct ones and it should work.