Really weird problem with my contacts and texting

I sent a text to a friend of mine a while ago, however, the message sent to a different friend. I didn't confuse the text threads or click the wrong contact. It went to completely the wrong person. A couple of days later, when that friend texted me, it came up as from her name on the notification screen, but in my message app, the text is from the other friend. I'm super confused. Please help! Or let me know how I can clarify the problem...