I bought my BMW motorcycle in September of 2016. It was new, with a new BMW Navigator V GPS (which is a Garmin).
I don't remember exactly when this happened, but sometime in the past 6-12 months or so, a bunch of mystery track info has shown up on my GPS. I usually download all my track data once a year and then wipe everything from the device. On this occasion, there were a bunch of tracks from 2015, and one from 2000. They were not there before. A lot of the data looks very much like someone commuting back and forth between two points. There's even a "Home" waypoint in Kanata, Ontario. I don't live in Kanata! (doubly odd ... the "Home" waypoint for my actual location is in the right place, but under "Contact Info" has the address of a Petro-Can gas station in Casselman, Ontario, which is a frequent waypoint in the tracks of this mystery data.
They are not just corrupted tracks of my own ... they describe routes that I have never ridden.
I also cannot delete them from the GPS. If I delete everything from my GPS, all history, saved waypoints, everything, and then reconnect the GPS to my laptop, there's the bogus route data again. In fact, there's track data and waypoints of my own that I can't delete either. I just finished wiping everything from my device and there's still old tracks and waypoints visible from within Basecamp:
None of this is stopping me from using the device.