Message coming twice

[leysard 10]

Hy, I'm buiding my first scripted mission and when I'm in Multiplayer and I serve the mission, the following task comes twice in my map. Could someone help me out to find the mistake ?

By the way, the _MissionMessage does only come once on my screen and in over players screen.

if (!isServer) exitwith {};
{
Task_2Data = player createsimpletask ["Task_2"];
Task_2Data setsimpletaskdescription [_Task_2Description, _Task_2Title, _Task_2Destination];
Task_2Data setsimpletaskdestination [_Task_2Gridx,_Task_2Gridy];
Task_2Data settaskstate "Created";
Task_2Mark = createMarker ["Task_2Mark", [_Task_2Gridx,_Task_2Gridy]];
Task_2Mark  setMarkerShape "ICON";
"Task_2Mark" setMarkerType "selector_selectedMission";
"Task_2Mark" setMarkerColor "ColorBlue";
"Task_2Mark" setMarkerText _Task_2Title;
playSound "Newtask";

_MissionMessage = "
<t color='#2159D1' size='1.6' shadow='1' shadowColor='#000000' align='center'>
Kill the informant !</t><br/><br/>
<t color='#FFF700' size='1.3' shadow='1' shadowColor='#000000' align='center'>
Kill the informant before he send's out information about our operations !</t><br/><br/>
<t color='#EEEEEE' size='1' shadow='1' shadowColor='#000000' align='center'>Check your tasks for more information</t><br/><br/>";
GlobalHint = _MissionMessage; publicVariable "GlobalHint"; hintsilent parseText _MissionMessage;
} forEach (if ismultiplayer then {playableunits} else {switchableunits});

Thanks in advance for the help