Originally Posted by Davy

You ask them to stamp the copy stating it is identical to the original.
Try to make them stamp it on the front. Leave place on the copy for the statement.

I went to the municipality office. It's the cheapest option here.
They stamped it on the back, which makes the copies worthless for digital transfer.
Luckily, the back was shining through when I scanned the docs. It was accepted by SKNAB.

PS: Why are you sending your docs so late?