Which manufacturers coupon is selected at Walgreens if you have multiple?

Hi! So I’m trying to get into couponing more (on a basic level), and one thing I’ve noticed is that sometimes I’ll have 2 “conflicting” manufacturers coupons. I was wondering how the system decides which one to use when checking out (since you can’t use multiple MCs), and therefore if I should/shouldn’t clip any and all applicable coupons?

E.g. 1 coupon for $3 off an Olay body wash 1 coupon for $1 off the same body wash

Obviously in a match-up between these too I’d prefer saving $3 instead of $1, but I wasn’t sure what the system at Walgreens would decide? Is it better to only clip the best one or will it start by taking whatever the best one is anyway?

Thank you!