Since the Cairne/Perenolde realm merged with Cenarius today, there is a massive bug with auctions. I and many others have dozens and dozens of items that have duplicated. Mainly battle pets, gear and even some mounts that we had on the auction house when the merge was being done that have now duplicated. What in the world is going on? I sell so many pets especially because I farm old raid on multiple alts, it was extremely hard for me to tell in some cases which were my originals and how many duplicates I had. As I was really afraid to relist the duplicates on accident and then get in trouble for it. What am I supposed to do, and how do I tell which are my original items? What is going to be done about this, and what are we supposed to do with all these duplicate items?
I had the same thing happen to me. I had a lot of boe’s for sale and a strong anti venom recipe that didn’t sell. I’m not sure about all the boe’s that didn’t sell but I do know for certain I only had 1 venom recipe. Now I have 2. I submitted a bug report but am hoping that was not a mistake. Hopefully Blizzard appreciates honesty.
There is another chain about this issue happening on Ravenholdt with the realm connections (Issue with recent server connection - #6 by Cilana-moon-guard). I also reported the bug, and opened a ticket because my bags blew up and I do not need to get in trouble or add to my space issue by using the AH while it is broken. I’ll let you know if I hear anything on my ticket before I see a GM reply here or on the other chain.
Yeah I have trust issues after a few years ago when they banned my account because of a pet I bought. The seller who listed it apparently was using a hacked account. But that had nothing to do with me! But they banned anyone who happened to buy items they listed, which is very bs. So I had to go through the whole drama of getting them to investigate my account, and see it was legit and reinstate it. They of course appologised ect, but it was traumatic and a pain. So I have major trust issues with them now. So here I sit with a ton of stuff clogging up my bank and bags now, because I am afraid of accidentally selling a duplicate it, even though it’s their glitch. But so far I have had no response from Blizz.
Putting this in both chains I am aware of on here:
So…this is the reply I got to my ticket. Basically, they know and are using the info to figure out, but keep the items until we see otherwise. I did tell them about this chain and the other, so hopefully they get it figured out soon. 
Game Master Kudaraphax here. I was able to do some digging here and I did find some reports on this that we have gotten sent up to the development team to be checked out. For right now though there is no word back on these.
I have gotten your information sent up to help with that investigation and if you have put in a bug report in game already then you have things covered from your side of things. For the time being its probably best to hang onto those items until we get more details.
For updates on this, I would advise keeping an eye on the breaking news and Bug report forums. You might also keep an eye on the hotfix blog here: https://worldofwarcraft.com/en-us/news/23277654/hotfixes-august-7-2020
I am sorry for any inconvenience this situation may cause. Thank you for your time while I checked into this.
I finally received a response "Hello,
Thanks for taking the time to get in touch with us and I’m sorry that I wasn’t able to get back to you any sooner.
I’ve just received your ticket regarding the possibility of having some duplicate items as a result of the recent server merge. Thank for taking your time to let us know, it truly was an honest and right thing to do.
I had a look into your character MageMarian (love the robin hood reference) and I have removed any duplicated items I could locate on the character. For yourself it didn’t seem that there was much there and you should be able to continue playing.
Thanks once again for giving me a nudge. Once more, I apologize for the wait, so thank you for your patience. Have a wonderful day and take care of yourself
All the best, o7
Iain {Mesmartiys}
Blizzard Entertainment Europe"
Only thing is I am like 99% sure that I didn’t have this many extras of these pets I farm, which means they did not remove them all. But then did remove like the extra gear ect. So I don’t know?? I guess I did all I could though, so I am just going to go back to listing my auctions. And if anything comes of it, its not like I can’t have them reference back to their own Dev who assured me everything was fine now.