@R Neil Haugen is correct! Each project file has an ID inside it (you can't see it), and Productions uses that ID to track clips as they are edited around the Production. Because of that, it's important that within a given Production, no two projects have the same ID. If they do, you'll get this error letting you know. As described in the screenshot, Premiere Pro puts a text file in the Production folder that you can open up to see which projects have the same ID. All you need to do is pick one to keep and one to remove. You can use the Trash button in the Production panel to put one of the projects in the trash, which will also stop the error from happening, as Premiere Pro ignores any duplicates in the Trash folder of the Production.
When it crashes, Premiere Pro can often save a recovery project right next to the original in case there were any unsaved changes. In this case, the original and recovery project have the same ID and so they get you in this situation. Nothing to worry about, just decide which one to keep and put the other in the Trash.