The scale is intended for a single user to ensure accurate and consistent weight measurements. If the app identifies a weight that may not belong to you, you will be prompted to verify it.
You can also always delete any incorrect weights in the app.
To do this on an iPhone, tap on the profile icon on the upper left side and then tap on the weight tab on the next screen. You can then swipe right on any incorrect weights to delete them.
To do this on an Android phone, tap on the profile icon on the upper right side and then tap on the weight tab on the next page. Then, tap once on the incorrect weight to delete it.