It’s a “feature” that was introduced when the app was updated to support new Homey libraries, all sensors using alecto v3 protocol will show up twice, just select the one with accurate reading.
Don’t ask me for a better explanation than that, I don’t have that kind of understanding, but you can find some discussion about it in the dedicated thread for the app, I suggest you ask there if you want a clarification.
https://community.homey.app/t/app-pro-wireless-weather-sensors-reads-data-from-several-brands-of-wireless-weather-sensors/23532
