Why do I get my daughters contacts from her phone on my phone?

Are you sharing any third-party account which provides contact syncing?

Set up and use iCloud Contacts - Apple Support:

"Add Contacts from third-party accounts

If you store contacts in a third-party email service, you can add the email account to your iPhone, iPad, or iPod touch. Then, check that Contacts is enabled. All of the information stored in Contacts uploads to iCloud."

Are you sharing the same Apple ID?