Gradebook

If you view an item in tracker and look just below the issue description there are tabs called "All Comments Change History Version Control"

Make sure you All is selected. You'll then be able to see commits to the code repository amongst the comments.

Generally the final commit (and patch where the person created one) will contain all the changes. Where you see multiple patches they are typically because the person had several attempts at fixing the problem. That means you typically only want to touch the last patch. You do need to read any comments however just in case this isnt the case for a specific issue.