The "pd" prefix was commonly used in early file-sharing networks (like Gnutella or eDonkey) to denote "Public Domain" or specific "Private Dump" categories.
If you have about where you encountered this name—such as a specific forum thread, a screenshot, or a mention in a "disturbing iceberg" video—please provide them to help narrow down the search.
There is currently or widespread community documentation regarding a video file or internet mystery titled "pd mandytwin.avi."