Neither of those cert numbers are valid when I attempted to verify them on the PCGS site. If you have not done so I suggest you try and verify these two cert numbers yourself, here is a link to the PCGS site. https://www.pcgs.com/resources Up in the right hand side you will see an icon for verify, click on it and input your numbers, both the numbers you provided in your op (501172604, and 501172603) are not currently valid. Some reasons for this might include a typo error in your request/post, a mechanical error on the part of PCGS, and other reasons. You would need to contact PCGS customer service to determine the problem and see what can be done to resolve the issue.
Note I do not work for NGC just a collector giving you some free advice.