Google sync: Syncing with other phones on my phone and I'm getting their texts

[AC Question]

Hey there,
Since a recent update my google sync has been syncing me with my friends phone and now all their contacts are in my phone. I am even receiving their text messages. Unknowing it was their contact I blocked all contact with that person since I had no idea who it was. It turned out the block also went through to my friends phone and they no longer had the contact once I deleted it. Also their Facebook, twitter, and email accounts were showing up on my phone also. Again unknowingly I apparently deleted content that I thought was spam on mine. It turned out it effected their accounts when they logged in. Is this a common issue with google sync? When my friend and I talked about how I was getting weird texts and Facebook spam on my phone, we realized his account was synced to my phone. Is there a way to prevent this from happening?

 

[Android_meta]

Yes, this is a common problem that has recently surfaced with the new update. In order to provide the correct privacy for you and your friend please make sure to delete the account(s) and clear any cookies. Also try rebooting your phone once you have done this to prevent any unprovoked syncs once more. Unfortunately you are not the only one who this has happened to and Google and Android are working hard for the next update to fix any unwelcome syncs.

 

[Android_meta]

I'm only aware of this issue because it has happened to me recently. I had to call google myself and explain it to them.