Duplicate connection detected
I have been getting this error message repeatedly. It will keep popping up and flashing for several minutes or I just close the game and I have to wait for a while then try again.
This is a server-side issue so why are you popping up this error message to the user? Please fix this coming problem by reading the link below and fixing your servers.
If you are using Apache at least you should understand the problem now and be able to fix it in whatever code you are using.