I'm trying to link my account to a friend but we cant through the game. The game says that my account was already linked and cant be linked twice (I did never link it before)

Old account:
Name: Geroo
Accout ID: 10590665
Email registered: geroo.ebeerle.11@gmail.com
Server:69
Level:86

The new device account is:
Name:XX
Account ID: 21845918
Server: 69
Level:1

Thank you