Unknown names with numbers in my contacts

[Android Central Question]

I have 2 phones both Samsung J5 2017. I have lent one of them to a family member. I haven't used the old one for over a year. I believed it was broken so bought a replacement. They've removed my old sim and are using theirs (their phone broke)
Why has some of his numbers appeared on my newest phone? Is it because my 2 samsungs have somehow been linked? Its a complete puzzle. There are also 2 other contacts that he doesn't even know and that aren't even in his contact list. All these names and numbers have appeared in my whatsapp and contact numbers. Can anyone help shed any light on this? Thank you

 

[mustang7757]

Hi, welcome to Android Forums

I'd like to recommend creating a account so me or other members can assist you, as guest have limitations in replying here and if we need further Information to communicate with you.

I'll provide a link to register, please come back to your post so we can further assist you . Thank you
https://forums.androidcentral.com/showthread.php?t=409154

 

[B. Diddy]

Welcome to Android Central! Before you gave one of the phones to your relative, did you remove your Google account from the phone and do a factory reset? If not, then your Google account is presumably still on that phone, and any contact that relative is entering into the phone is going to your Google account, not theirs.