I appreciate very much the feature in shopify mobile app that it shows up when you give an sku to a product which already exists.
I use the app sometimes (would do it more often if i could choose the size of foto on shooting) and i find it very useful.
Why do you not implement in admin backend. I would safe a lot of time in double checking.
I am a one of a kind retailer which approx 3k of products growing.
Thanks for your attention