N64 cart misprint?

[RustyRetro]

Hi all, I'm new to this forum. I just aquired a few N64 carts and i noticed on the back of mario64 an imprint, at a glance I thought it was just damaged from use but the imprint looks about the same size as the imprint should be on the front of the cart buts its on the back. Have you seen this before? Where can i find more info about factory mistakes? Thank you!!

 

[crunchyg]

Is it indented or elevated? Are you sure someone didn't just use it as a coaster for their coffee mug and melt the plastic?