Thanks! I've not specifically checked for overlap but in theory they
should be totally fresh each week, unless someone reposts content. The Reddit scraping is done with PRAW [0] which checks through the top 500 submissions ordered by upvote count in the last week. I imagine it's the same process as ordering by top>"Last week" on Reddit itself. Since the bot runs at the same time each week there should be no overlap with the previous week, but it probably depends on the Reddit API and how it interprets time.
[0] https://praw.readthedocs.io/en/stable/