That is a tall request. One thing that is looked for by some of the experts is the hand-eye-curve. This is to see if it looks like the same 'brain' made both or comparable items. Like, if the Scroll is original to the Bass? Same hand, same maker?
Like with these 2 Pollmanns, one of which I have since sold. One made by
the father and one by
the son 23 years later! What are their differences or similarities? You tell me!
On German and French Basses from the latter half of the 19th and first half of the 20th centuries we see Scrolls on various Basses that look to be the same. This means that the makers in France 'bought' the Scrolls/Necks and put them on their Basses. The Germans did the same thing in Germany. This is not 100% for every Bass made in those 100 years but it was a practice due to the Guild in place like Unions. Scrolls were made by those in the Carving Guild.
Ask Arnold who makes Basses by hand to show if he can, 3 or 4 of his recent Scrolls and see how they compare. These we know for sure were carved by him personally, not purchased. Then with certainty, we can see how a single maker can vary from Bass to Bass.