Hi, thanks for your post.
I don't believe there's any way to do this. Each commit gets its' own revision number as you know, and there's no easy way to look at multiple ones of these at once. This is because, following your example, the same object could have been changed in multiple commits not only by one dev, but several. As the histories are cumulative, the later one would include earlier changes but of course it does include things from other devs if they committed in between.
In an ideal world each dev would commit at the end of a given job so that all the work for a certain task is grouped in one commit... but I do appreciate that's not always going to be practical.