PreRepositoryCommitHook gets fired only once even for multiple commits, but post repository hook gets called multiple times

I am developing a bitbucket repository hook plugin. It works well when I commit and push at once from SourceTree. I mean I do a single commit, and I check the push changes immediately option.Capture1. The PreRepositoryCommitHook catches it well and I can access the commit message from the callback setup. When I create multiple commits, and do a push at once, the callback only gets called once, and I get the latest commit’s message, whereas the post repository hook gives me all the commits one by one, i.e., the callback method gets called multiple times one for each commit.
My question is how could I get all the commits’ messages in the prerepo hook?