I must admit I'm split here... during testing, both software and signatures, we often re-scan right away, so disabling the Start button after a scan feels unproductive.

During most dialogs, Yes and No buttons are next to each other and are also contradicting choices. I remember the annoyance of many programs not following the standard, so Yes and No are swapped sometimes, which can create issues.

The idea of a confirmation dialog - if the list contains previous scan results - sounds quite good to me, I'll see if we can still squeeze this into 2.8.