When I add a book to my collection, when selecting the issue, books I already have in the collection have the issue number highlighted blue. But when I use the check value function there isn’t an indication of whether I have the book already or not. It would be very helpful to have that functionality.
It seems you’ve found a bug. This should indeed work.
I’ve checked on Android: it shows it correctly on the Cover/Barcode/Issue tab of the Check Value screen.
On iOS it only works on the Barcode/Issue tb of the Check Value screen.
Not on the Cover scan tab.
I’ve posted the bug in our bugboard for fixing. My apoloigies for the inconvenience caused.