Out of curiosity, what carrier are you on? I ask, because my wife had been having the same problems for a few months, when she would send pictures to her mom, they would always come through looking screwed up, similar to how you describe. Both her and her mom are AT&T, my wife on an LG V10 and her mom an iPhone. They would come to my phone okay, but always two copies would come through. I'm on AT&T as well, but I was using a low-end unlocked phone (BLU Life One X) at the time, which didn't take advantage of any of the newer AT&T network features.
Fast forward to now, I'm on my new Note 7, and the first time I open the stock messaging app, there's a pop-up about using Advanced Messaging. I click okay to go ahead and use it. Then my wife goes to send me some pictures, and now they come through the same way they were going to her mom, screwed up.
I've been busy with other stuff since then, so I haven't had a chance to try and send pictures to her to see if they have the same issues and try to see if turning off that Advanced Messaging helps anything. I say all that to wonder if your problem could be the same or similar and may have nothing to do with the phone but instead an issue on the carrier side.