Target’s annual car seat trade-in event is back now through April 30 — and with a coupon. The retail giant is offering a 20% off coupon customers can redeem twice and combine with other sales when they trade in used car seats or bases. They can use the coupon in store or online toward baby gear, including a new car seat, stroller or high chair, through May 14. The full list of items can be found here. However, customers must sign up for the free Target Circle Rewards Program to qualify. Some deals in Target’s 20% off baby gear sale that you can stack with the coupon include: $255 off Keenz XC …