forward TimedCountdown(playerid);
public TimedCountdown(playerid) {
    if(iTimedCountdown == -1) {
        iTimedCountdown = 81;
    }

    new
        szMessage[10];

    iTimedCountdown--;
    format(szMessage, sizeof(szMessage), "~r~%d",iTimedCountdown); // Add more in if you wish.

    GameTextForPlayer(playerid, szMessage, 950, 6);

    if(iTimedCountdown == 0) {
        KillTimer(Sfracetimer);
        DisablePlayerRaceCheckpoint(playerid);
    }
    return 1;
}

forward TimedCountdown1(playerid); // Also make a new SetTimerEx function in which you just add the number 1 in the funciton name.
public TimedCountdown1(playerid) {
    if(iTimedCountdown[1] == -1) { // Under there on iTimedCountDown put: new iTimedCountdown[2];
        iTimedCountdown[1] = 81; // At the other timer put : iTimedCountdown[0] Or you can do it it like this:
    }
/*    if(iTimedCountdown1 == -1) { // UYou need a >> new iTimedCountdown1;
        iTimedCountdown1 = 81; // Just uncomment and comment the other one.
    }
*/
    new
        szMessage[10];

    iTimedCountdown--; //  v down there, I have put ~n~ because that makes a new row, you don't want the timers to be in the same row and get one over an other.
    format(szMessage, sizeof(szMessage), "~n~~r~%d",iTimedCountdown); // Add more in if you wish. 

    GameTextForPlayer(playerid, szMessage, 950, 6);

    if(iTimedCountdown == 0) {
        KillTimer(Sfracetimer);
        DisablePlayerRaceCheckpoint(playerid);
    }
    return 1;
}