So I was entering information for #105: The Smoke Screen Mystery (https://www.hardyboyscasefiles.com/series/originals.php?book_no=105) and noticed that the ISBN number on the inside of the book was not the same as the outside of the book. It appears the inside ISBN number is a Nancy Drew book. Does anyone know if this was corrected with different printings (were there any other printings)?
In the late-80's, early-90's S&S gave books new ISBN's with each print run. So if you look at a first printing vs third, you'll usually see a different number.
I've got different ISBNs on my copy too. Yeah, it is probably an error that was fixed in later printings.