Joomla 1.0.12
VM 1.1 r928
Try the following, in Extended Layout view Products -> Add Product, add a product for example.
SKU - watch001
Name - Casio watch
Price (Net) - 9.99
category - Hand Tools
Click Save, a save successful message is shown, view shouldn't have changed it shows the product you just typed, now change the price to 19.99 and click save, you will get a message 'Error: A product with the SKU watch001 already exist'
Hence when, Saved button is pressed and save successful message is show it should return to product list view or add an Apply button to allow changes after apply is used, like Simple Layout view.