Hi @nd62,
the author box at the top is being displayed because it “belongs” to the page you are inserting/injecting into the post template.
We have added a compatibility function to prevent the author box to be added to that injected content when using the Publisher theme. It will be available in version 4.2.0.
For those facing the same issue when injecting content into another page (using the Publisher theme), there is a workaround you can take: edit the page being injected and configure it to not display the author box (Authorship Box > Display > Hide).
Thanks for reporting the issue!