Many authors get famous for the first book they write. There is a great idea that is delivered at the right time. That popularity normally offers them the opportunity to write another book, as publishers clamor for a repeat of their current success.
The second book often doesn’t do as well. There are a million reasons why. Many of those reasons are connected to the next book not being different enough from the first. Authors are asked to write a sequel and it is hard for follow-ons to do well in the non-fiction space. The core of the idea was pored into the first release and as readers, we think there isn’t much to improve upon.
I think that is wrong and that you are missing something.
If the first book was successful, the author is given opportunities to presented those ideas dozens of times to conference audiences and executives boardrooms. The ideas get improved. The language and metaphors shift. You’ll find the author can summarize his main points more clearly in a few paragraphs than when he could across several chapters in the first book.
The 22 Immutable Laws of Marketing by Al Ries and Jack Trout is the more succinct version of Positioning.
The Clay Christensen’s Innovator’s Dilemma is great, but Innovator’s Solution is better at describe the original problem and solution.
So, if you like the first book, consider again picking the second book for the opportunity to get an even clearer sense of what the author has to share.