Knowing what could happen on each device is key to identifying doubled dies. The doubling is usually in the same places, but with different strengths. The devices might be doubled at the top, middle or bottom. So knowing what to look for helps a lot. Study the listings and read what he is showing as hub doubling.
This sounds like a subject that should be prepared with each coin series? I wonder who could do that? LOL It will take some times to put this together, but I'll try to get something soon. Not today, but maybe later on. But for now, check out Brian's varieties. Take notes Copy images into a word program. Get the sense as to what can happen on hub doubling. Keep in mint that in a series, that the same types of doubling can appear on any other year. Stronger/weaker spreads are possible. I have a word program file of just 'Coin Information.' You know stuff that you read and want to remember. You can copy images from the threads. (but you can edit them or post these) but the information is there is you little word folder. Highlight, right click, past them to your word folder. (mine is in the 100+ pages) Stuff you want to save, you don't want to write down, tags from websites links. There is no end to what you might save. I wish I had started mine with different files for Cents, Nickels ETC, Errors, storage information as separate folders. So you might want to start that today while your starting to learn about a certain subject. Hope this helps.