I've deleted all my texts, but the next time it happens I will try to remember to send a screen shot. In short, when I send a text to someone and it looks like I received a text back, I check and don't see their answer until I look above my original text. It should be below my original text.
I looked up Carnac and saw nothing that would help with this problem. I also looked up the johnny carson link and only got info about Johnny Carson. I guess I will just deal with it. Thanks, though.
I'm with you. The only Carnac malware I found is a Facebook exploit. I can find no reference or explanation for your Messages issue. Perhaps a screenshot would help us understand what is happening.