Dallas here from the Social Care Team at Shopify.
Thank you for adding all of this information for me. I tried this out on my personal mobile device and all the products only added once so I wasn't personally able to replicate this issue.
Have you heard of this issue from more that one customer or is this something that you just noticed from time to time?
If it is just something that you've only noticed so far then are you able to try on another mobile device to see if you're able to replicate the issue there? Without a bit more information or some examples, I won't be able to take this to my tech team quite yet, so if you could take some screenshots of the instance when it happened as well as the time that this happened and the device that you were using that would be very helpful.
Please let me know if you're able to see this issue on another device.
Hello Dallas, thanks for getting back to me. It's happening for more than one customer, people have had to return items because they didn't realise they'd ordered two. It seems to be happening often with the Lia in Navy, and only on mobile https://teatandcosset.com/collections/tops2/products/lia-knit-top-navy
Not all the time though.
I see! Ok, thank you for letting me know.
Have you made any changes to your store recently? Added any apps or anything? Maybe made adjustments to your theme code?