This happened to me today. I could only find info about it from a year ago claiming it was a one time issue. Also back then they said it was sending previously sent messages but this was a text I definitely never typed because it was in a language I don't speak. No idea how this happened.
I just joined community for this very reason! This same thing happened to me yesterday - 10/14/20. It was sent to my partner who has a Samsung (as I do) but is not on the same plan. It was sent right after I sent an actual message, but the second message was one I definitely didn't type or send. I haven't had much luck finding info as to why it happened but I am a little relieved that other people are having this same issue.
Hey, good morning. I'm aware of this issue, a lot of persons has been encountering this issue as of lately, but it's so strange. I'll provide all the troubleshooting steps I can because I know how this situation can be. Are you aware of any virus on your device?