Hi Nov
This happens sometimes where more than one post of the same article gets posted and only one gets upvoted. If the links are both clean (which both are and are only differentiated by a "/" at the end in this case) it will then depend on:
1. Where they appear in the feed (i.e posted with more REP for the Relevant Section or posted with more coins for the Hot feed.
2. How are high REP users curating that period. (i.e starting in the Relevant section and working downwards or starting elsewhere and working upwards.)
All can do is apologize that yours got missed and encourage you to keep going with your journey on the economics feed as once you build up some REP, and maybe even obtain some REL, you will have more "presence" on the feed and your posts will be less likely to be missed.
In the future if you have any further queries like this then please post them in the support feed. 🙏