Hey there, and welcome to Apple Support Communities, sikoal!
From our understanding, your Apple Health data is being shared between two devices. We’d be happy to help shed some light on this!
You mentioned that you’re sharing an Apple ID, which sounds like it may be contributing to this behavior. Since Apple Health data is shared using iCloud, you’d want to go to Settings > Tap Name > iCloud > Health, to see if that is enabled. If so, it will update and share information across devices.
While you can disable that feature, you can also create separate Apple IDs and set up Family Sharing, which will allow you to share purchases and keep your data separate. You can also share iCloud storage, if that is a concern. You can read more about that at: Family Sharing - Apple and Set up Family Sharing - Apple Support
If you’d prefer to go that route, How to create a new Apple ID - Apple Support can help and What to do after you change your Apple ID or password - Apple Support can walk you through the steps to be sure the new Apple ID has been updated everywhere.
Let us know if that helps, and have a great day!