This error occurs when you have more than 3-4 separate text messaging conversations are going on and the messaging application gets confused and sends the message to the wrong person. Like if you are texting to A,B and C and continuously you have been opening the notification bar to view the text and reply and you press the back button to A and then go back and reply to B and then to C and now when you press back and go to reply to A the messaging application will automatically send the message to contact B or C.
You might not have noticed this bug because you open the messages using the messaging application, you close every conversation using the back button and don’t let it work on top of one another, or you might have avoided it.
I recreated this Bug in this way:
I opened a text directly from the notification bar and i went to the conversation with that contact, then I hit the home button to get back to the home screen, I repeated this four times so now there are 4 contacts now open and I am texting to all of them simultaneously without hitting back and closing the conversation. Lets say I did this texting procedures a few times and have send more than 5-6 messages to each of the 4 contacts in this order, contact 1, me , contact 2, me, contact 3, me, contact 4, me, etc. and now as soon as i read the message of contact 3 again and reply and then hit back to reply to the message of contact 4, now you are back to the conversation list and select the 4th contact you write and send the message but what can actually happen is that your message will be sent to contact 1 because there is a bug. This is a major issue right now and I guess Google should look into it and solve it as soon as possible.