Shared trash between two computers
My company has a MacBook that used to be mine when I worked at another office, it was signed into my apple ID and my own login. I transferred to another office and a colleague was given my old MacBook. The old computer has a new login for her, a new Apple ID, and she is the admin on that computer.
The old computer has files in the trash that my colleague didn't recognize. They are items I had put in my trash earlier that day. It's been a year that she's had this computer, and we just started to notice this. We are not on a shared work server. Is it a virus? Or does this usually happen to computers?
MacBook Pro, OS X El Capitan (10.11.6)