[Boarden]

Try this, use strcmp to compare strings instead of "==".

Code:

if(strcmp(Account[i][Username], name, true) == 0)
{
	SendClientMessage(playerid, COLOR_ERROR, "Someone is already connected with this account.") && SendClientMessage(playerid, COLOR_INFO, "Please login with a different username.");
	SetTimerEx("KickTimer", 200, false, "i", playerid); 
}