Custom Sequential Workflow creates 10 items for 1 event in Calendar

Question

I had created a Custom Sequential Workflow in Visual Studio 2010 which runs when any Event is added in Calendar List. I have created a Custom Column named "Sequence". Now when I create any event in calender, Workflow Starts and makes 10 additional entries for same Data. What should I do to prevent it from creating 10 additional Entries?

This is How it looks when i create a new Item.

My Code is as below.

            SPWeb web = workflowProperties.Web;
            SPList Calendar = workflowProperties.List;
            web.AllowUnsafeUpdates = true;
            Random  randomNum = new Random();
            SPListItem calendarItem = Calendar.Items.Add();
            calendarItem["Sequence"] = randomNum.Next();
            calendarItem.SystemUpdate();
            web.AllowUnsafeUpdates = false;

Answer 1

It could be that your workflow becomes recursive.
If you update the item you could try using SPListItem.SystemUpdate.

Answer 2

   I tried this and it worked.

    SPWeb web = workflowProperties.Web;
    SPList Calendar = workflowProperties.List;
    Random  randomNum = new Random();
    SPListItem calendarItem = workflowProperties.Item;
    calendarItem["Sequence"] = randomNum.Next();
    calendarItem.Update();