If you're looking for an answer as to why one was added but not the other, you could be in for a long wait.
Concentrate on resubmitting the one without a listing. If it's worthy, it'll be added eventually. However, if they are both interlinked Yahoo will judge that they are parts of the same site, so don't link them.
Also, read the next Despatch, it's coming soon, I promise(!!) There will be a lot of insight into Yahoo, the likes of which have never been seen before ;)