Are dual-outlet outdoor smart plugs worth the price premium over single-outlet?

For most use cases, yes. Dual-outlet models like the Kasa EP40 and Tapo P400M let you independently schedule string lights and a fountain or holiday inflatable from one weatherproof enclosure. Reviewers on r/homeautomation and r/smarthome repeatedly recommend dual-outlet Kasa over single-outlet alternatives for exactly this reason.