You got it. There's only one prize for multiple sweeps.
One thing you forgot though is the sweep that doesn't list the participating sweeps in the rules. The only thing listed is "creative presentation" or similar verbiage. You've no way of knowing how many sweeps are participating - it could be 5 or it could be 50 or more.
Check the introduction in the rules for this sweep (lower left corner):
https://castlebrands.promo.eprize.com/irishtothecore/?affiliate_id=Sweepsadvantage
Creative presentation is the only thing disclosed, so how are you going to find the other participating sweeps, and how many of 'em are there?