Hello everyone! 
That would be the problem that makes it twice as the vehicle 
Also, do not print the chat to a vehicle stocked. 
The code: 
 
  
function Autocsinalas(thePlayer, command, vehicleModel) 
    local x,y,z = getElementPosition(thePlayer) 
    x = x + 5 
    local createdVehicle = createVehicle(tonumber(vehicleModel),x,y,z) 
    local vehname = getVehicleName (vehicleModel) 
    outputChatBox("A lekért jármű : "..vehname.." ("..vehicleModel..")",thePlayer) 
    if (createdVehicle == false) then 
        outputChatBox("A jármű lehívása sikertelen.",thePlayer) 
    end 
end 
addCommandHandler("veh", Autocsinalas) 
  
 
Thanks in advance! 
Sorry for the bad english! I used google translator!