If you have two (or more), should the hook and inciting incident be the same? Should they have different themes and epiphanies/aha moments? I'm talking about story progression, not official beats.
The character arc is unique to the character, so each protag may have a unique inciting incident, unique goals and face unique obstacles. The arcs of multiple characters may intersect throughout the story, or they may have little impact on one another, but the various plotlines should eventually have a meeting place, should be linked in some way, converging somehow near the end of the story, such as at the climax. K.M. Weiland covers this topic well in the following article: How to Structure Stories With Multiple Main Characters?
I don't really use story beats like inciting incident. I mean, I have them, most of them, probably, but I don't use the formulas. I'm less than a chapter away from finishing a ~155K novel with many story threads and character arcs. I think the trick is to introduce things like inciting incident at times natural to the arcs. I wouldn't worry about trying to time them together or have the stories all spring from the same event. Don't get me wrong. This could be done, but it isn't something you have to do. Try to find the beats as they occur naturally for each thread.
Beats are not formula, they are shifts in the story. Things going good in one scene, then the next scene shifting to either very good or bad. You can represent beats by ++ + - --. Just like life, beats change. When used well you can build drama.
Characters don't need to have epiphanies or aha moments in a story. I mean, they can, but they don't need to. I don't think any of my characters do. That can sort of be too on the nose or a way to wrap things up too nicely that it can sort of take away from the overall story.
It is much more interesting to have the characters struggle to learn a lesson, rather than it coming as an epiphany. Though that can be useful, after they have struggled and failed to learn a lesson repeatedly. Then have an epiphany moment resulting from their failures. Or perhaps their failures bring about gradual changes in them that they aren't even aware of. There are as many ways to deal with character change, as there are people. I think it needs to come down to the original characterization, as to how they handle the changes.
I'm terrible at multiple character arcs, but I understand from those who are better than me that whilst they can all have their own 'inciting incidents' and other such turning points, you will give the reader a real thrill if you manage to make one moment in the story be a turning point for multiple characters at the same time. Say, for example, for favourite character no.1 the moment midway through Act II is an "ah ha!", whilst in the corner, initially unnoticed by character no.1, or even the reader, favourite character no.2 has just had the bottom knocked out of their life by the very same moment and is quietly dealing with that. Its the kind of thing you see done with overbearing charismatic characters in the no.1 role, and their loyal sidekick in the no.2 role. In Sharpe's Revenge Sharpe and Fredrikson both meet the same woman, Lucille (the inciting incident). That incident sets Sharpe up for yet another happy ending that he didn't have to plan for or have to earn, and is largely unaware of at the time. Meanwhile Fredrikson is very aware of the moment, gets something to be hopeful about in his life at last (romance), which is horribly dashed at the end of the book by said happy ending, where Fredrikson saves Sharpe, thus allowing Sharpe and Lucille to announce their love, which blindsides Fredrikson, ruining his friendship with Sharpe and all hope of love. Two pivotal moments where one character's pain is another's gain and neither is an antagonist.
