Upvote:2
I'm not a scholar of liturgical history, but the lectionary for Sunday's readings and weekday readings have followed separate cycles probably since 1561. Additionally, both cycles lean towards giving readings appropriate to the season. As a result things get repeated for the benefit of those who normally only show up on Sundays.
If you want to learn more, I recommend checking out haligweorc a blog by Derek Olson who really is a scholar of liturgical history among other things.