This has been happening to me a few times a week for the last week or so. I texted my bank (mobile banking, I can send a text and it replies with my balance) and then it had "Jenn xxx" in the header bar. Freaked me out! Then today, I was having a conversation and everytime I replied to the other person, my message was sent to my email, not to her! Header said "Email" (which I have programmed into my contacts to send myself a pic msg quickly). I looked in the message details and it said the # it was sent to was 6245. No idea what that is. If I then forwarded her the message, it worked fine.
And finally, I did have an instance a few weeks ago of a message actually going to the wrong person. On my lunch break I ran an errand and then to pick up lunch for my coworkers and some clients, and the errand took longer than expected, so I texted a friend/coworker "on way back now, @$$tards at pharmacy took forever!" Then I got a message from my sister that said "HUH???" Although the message I sent was in the thread between myself and Maggie, when I viewed the details of it it listed my sister's phone number! It did not appear in the thread of messages between my sister and me. *This* could really cause problems if a message got to the wrong person; I often vent about a client w/ my coworker or husband, and said client is in my contact list as well. I think if I got fired because a message went to an unintended recipient, I'd definitely be looking into my legal options!