We are not folks that work for Apple. We are not going to “pop up on [your] iPhone”, either.
Of the previous four or five times, what has been suggested about SIM cloning? That’s typically an issue between you and your cellular provider, and whether youmare allowing physical access to your SIM, and your cellular provider’s security against this.
Contact your cellular provider about this, as this is a carrier issue, and as a cloned SIM will show errors when both phones are active on the network.
SIM cloning is entirely separate from your Apple ID, save as a path to reset that password. Which you would notice.