The data source for the duplicated weight entries is Apple Health. Your Apple Health is syncing the weight that is recorded from the scale and adds it again to the Allurion app, thus causing the duplication.
Please follow these steps to disconnect your Apple Health from Allurion app:
On your iPhone, go to Settings > Apps > scroll down to find “Health” app > Data Access & Devices > Allurion > Turn Off All.
If you use Apple Watch and you need other metrics or physical activity to be shared with the Allurion app, you can simply disable "Weight" from being shared, and the rest of the measurements will remain.