Wow, this is unfortunate. It's hard to be objective without having both books in hand, but after looking at Alphonso's video, yes if you cherry pick pages and compare them side by side with Jake's book, they do look very similar. I feel like I could also take Alphonso's book and compare them side by side with a couple of Andrew Loomis books which were first printed in the 1940/50s and get similar results, especially in his lighting/shade and value portions. Both books use similar theories, tropes, and drawing examples I've seen over many art books, classes, and tutorials.
I always hope to find a selection of art instruction books that are similar enough to reinforce the same concepts, but presented with the author's unique voice and art style.
If you look at quick flip-throughs of each book, they both look very well done, and different enough that they could reach different audiences with some cross over. Alphonso's looks very well articulated and gives a more traditional, serious vibe to it. Jake's seems a little more trendy and formatted to be possibly more easily digestible with how the information looks like it's broken up. It's what I might expect of any two books covering similar subject matter. The value of that is that you get similar concepts explained by two different artists, with different art style examples, and variety in the exercises offered- something I've always found to be very helpful.
That's my initial gut reaction to the situation. I do have a bias toward Jake as I wasn't familiar with Alphonso before this- though he looks like a great instructor and his book looks very good.