new bool:OamtDialogOffen[MAX_PLAYERS];
new bool:BrauchtHilfe[MAX_PLAYERS];
ocmd:showauftraege(playerid) {
    //[..] ShowDialog(..)
    OamtDialogOffen[playerid] = true;
}
ocmd:auftrag(playerid) {
    if(!BrauchtHilfe[playerid]) {
        BrauchtHilfe[playerid] = true;
        for(new i = 0; i < MAX_PLAYERS; i++) {
            //[...] IsPlayerConnected, IsOamt etc.
            if(OamtDialogOffen[i]) {
                ShowPlayerDialog(..);
            }
        }
    }
}
public OnDialogResponse(..) {
    if(dialogid == OAMT_DIALOG) {
         OawmtDialogOffen[playerid] = false;
    }
}