"Blood Feud" is explained on the article:
This episode was part of the second season production run, but was completed behind schedule, so it was broadcast after the normal season run as part of Fox's "premiere week", which during, Fox aired new episodes of their top shows. The reason for this is so they could gain new viewers for the fall. This episode is considered a second season episode, being part of The Complete Second Season DVD boxset.
As for Lard of the Dance, it is unknown but could be for similar reasons.
