they are not NIB.
hornady has their own head stamp. also if I understand you correctly you only purchased the brass and the boxes state a bullet weight, only found in preloaded ammo. what you bought was somebodies used brass which they reboxed and sold to to your local gun store. I will agree with the assessment that one was mistakenly fired from a 30-06 and the casing fire formed out to the chamber dimensions while the other appears to have been fired from the proper chamber.
EDIT: I just re-read the original post. you say that the PPU/PRVI blows back?
stop firing at once and take it to a gun smith to verify chamber.
I will almost bet that your rifle was bored out to 30-06.
ignore my complete lack of capitalization. I still have no problem correcting your grammar.
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