Contacts crossing to spouse's phone
I manage the iPhones for a business and have a couple couples who are getting each other's contacts on their devices. They are not using the same iCloud account.
They are using iPhone Xr; iPhone 11; and two are using iPhone 12 Mini - all on iOS 14.6
I'm sure there must be some common account, but how to find it? I've verified they do not have each other's iCloud accounts signed in on device.