Can someone legally file/record a grant deed from themselves to someone else and record it w/o telling the new owner?

An individual can record a deed from themselves to someone else because the county recorder only requires the transferror's notarized signature on the deed. The county recorder will accept the deed without the transferee's permission. If you as a transferee do not want to have the recorded deed to be used to transfer title to you, there are methods you can take. However, it is best to consult with a real estate attorney to analyze the pertinent facts of the case in order to properly guide you. Your easiest way out is is probably to find someone that wants the property and deed it to them.

Physically and practically it happens all the time. I do not understand your use of the term "legally" because you imply something else.