[Jefff]

pawn Код:

new pLastMsg[MAX_PLAYERS][129 char];

public OnPlayerConnect(playerid)
{
    pLastMsg[playerid] = !"fghsfhdf";
    return 1;
}

public OnPlayerText(playerid, text[])
{
    if(!strcmp(text, pLastMsg[playerid], true))
    {
        //Have wrote the same message
        //Do something
        //return 0; to prevent sending the message
    }
    strpack(pLastMsg[playerid], text, sizeof(pLastMsg[]));
    return 1;
}