Actually, the date is absolutely correct, since it's the second printing, as seen on the cover. But the linked info is for the first print.
I don't see how this could be a 1965 reprint, as the cover would have been changed to the new Dell Comics logo that started in 1962 during Dell's transition period to ending their distribution/production deal with Western Publishing, and with Dell producing their their own titles in-house, after Western would take most of Dell's previous leased properties with them to be issued on their own, Gold Key Comics. The series that issued this book with #1235, Dell's Four Color Comics, was ended with #1356 in early fall, 1962. In spring 1962 Dell changed over from their "stamp logo" from their "Dell Trading Post" Period, to their last ("Streamlined") logo. The latter would have looked like this if it had been reprinted in 1965:
and it would NOT have had a Four Color Series # of 1235, or ANY issue number on the front cover, as that series was discontinued in late summer or early Fall of 1962. The last set of numbers in the issue code under the Dell logo on the comic book above from 1963, would have been the series format for an issue in 1965. The 3 stands for the last digit in the year of issue (1963). it would have been a "5" representing 1965. The last 2 numerals represent the month (11) for November. The number for May, 1965 would have provided the code of -505, for May of 1965. Even a 100% clone reprint of the 1961 issue would, in addition to the newer Dell Comic Logo, have also had a new different indicia, representing new information, and the new agreement with UPA, rather than the 1962 indicia we see on the 3rd page of this book.
Therefore, this book seems to be the 1961 produced, early 1962 printed and distributed issue. I'd be shocked to find out that Dell issued a reprint of a Mr. Magoo in 1965. I doubt that UPA's deal with them lasted after the end of 1963.