My reasoning for the warranty block with a later date casting is that (if) it had actually had a warranty replacment back in the day, most often the block would be cast in a later production model year, If you were getting judged at OE either one would get you the same score, with the ICCA OE judging no extra points are given for numbers matching, it was decided to let that slide to leave less incentive for a builder to restamp a block in an effort to gain points. We would not want to promote such an edeavor even indirectly.
