A player has two accounts in the same 100-people world. A player used the first account to join it and played normally. However, that player used the second account to declare war against a lot of different countries. The morale of the victim is affected. Bytro, I hope there are some measurements to solve this issue.
Thanks
since they removed our ability to report players easily through the report player button. you have to go the long way around now by going to settings, clicking submit bug report. then describing your report there. you have to manually input ALL the details so be as descriptive as possible. reporting multi accounters used to be so easy 
now its hard , why? who knows
You can report in support. They can check, if the claim is legit, they would ban both accounts.
