Most of you I am sure already know of this duplication glitch involving your faithful companion Dog Meat. But to those who do not know I'd just like to say this, do not do this glitch. It brings bugs into your game that are too annoying to be worth it. (At least to me personally) From characters being on roofs to your faithful companion not being obedient; from unexplainable happenings in game to corrupt save files.
And, if your glitch happens like my own, it doesn't even work for most items. See I like playing games realistically and having patience for in-game experience. I personally was going to only arm up my settlers with my current armor and weapons. Hey, I just want my people to have the best things.
Think about this, if raiders were a constant threat in our world (If we ourselves were in fallout) and the settlment you've created and the people you've saved are in threat, then I'd do my absolute best to arm up my friends with the best armor and weapons.
So anyway, armor didn't work and weapons didn't work. But I did get a bunch of bugs that I truly hope are fixed.

I'd also do my best to be a citizen tester for you guys if you contacted me 馃憢馃徎
Have a great day ~ LukeForTheNight

I tried it, but I cant get him to find any items at all. I had him find a container once, but that was the only time I could get him to find anything at all.

Hey there man, Of course I have no idea how well you're able to have the game work for you but just hear me out while I walk you through speaking to your dog.
Go up to your pet and simply press A, (for Xbox) or X (I do believe, for PS4). That gets your dogs attention and while you have that be sure you're close to that pet of yours and then it should definitely let you press up to four options of buttons.
At 0 degrees (North) it should say Talk, ((while you're looking at that pet of yours)) so go ahead and hit that. Now a whole new set of options should show up, and please forgive me I haven't seen these options for a bit I currently have Prestion as a companion ((Forgive me again if I spelt that wrong)) Anyway you should see an option that says something like, fetch. Hit that and a whole new set again should show up giving you the choice of items, enemys, and two other button choices. Choosing Items will let your dog find whatever is close to you and your pet. But be sure you're somewhere that something could be hidden. A cave, a building room, around cars, robots, bodies, or some kind of structure.
I do realize that I'm not doing well at all to explain this but I do also believe that that is only because I haven't had my dog as a companion for quite some time now.
Have a great one ~LukeForTheNight