public void CopyList(SPList src)
{
    //Copy items from source List to Destination List
    foreach (SPListItem item in src.Items)
    {
    	if(isUnique(item.UniqueId))
    	{
    		foreach (SPField field in src.Fields)
    		{
    		   try
    		   {
    				if (!field.ReadOnlyField)
    					newDestItem = DestinationList.Items.Add();
    				newDestItem[field.Id] = item[field.Id];
    				newDestItem.Update();
    		   }
    		   catch (Exception ex)
    		   {
    			   ex.ToString();
    		   }
    		}
    		//newDestItem["wrkspace"] = src.ParentWeb.Name;
    		// newDestItem.Update();
    	}
    	DestinationList.Update();
    }
    // DestinationList.Update();
}

// ** Copy the fields
foreach(SPField field in sourceItem.Fields)
{
    if (newItem.Fields.ContainsField(field.InternalName) == true &&
        field.ReadOnlyField == false && field.InternalName != "Attachments")
    {
       newItem[field.InternalName] = sourceItem[field.InternalName];
    }
}

// ** Delete any existing attachments in the target item
for (int i = newItem.Attachments.Count; i > 0; i-- )
{
    newItem.Attachments.Delete(newItem.Attachments[i-1]);
}

// ** Copy any attachments
foreach (string fileName in sourceItem.Attachments)
{
    SPFile file = sourceItem.ParentList.ParentWeb.GetFile(sourceItem.Attachments.UrlPrefix +
                                                          fileName);
    byte[] imageData = file.OpenBinary();
    newItem.Attachments.Add(fileName, imageData);
}

// ** Remember where the original was copied from so we can update it in the future
newItem["_M_CopySource"] = sourceItem["FileRef"];

newItem.Update();

public void CopyList(SPList src)
{
    //Copy items from source List to Destination List
    foreach (SPListItem item in src.Items)
    {
        if(isUnique(item.UniqueId))
        {
          newDestItem = DestinationList.Items.Add();

          foreach (SPField field in src.Fields)
          {
             try
              {
                if ((!field.ReadOnlyField) && (field.InternalName!="Attachments"))
                  newDestItem[field.InternalName] = item[field.InternalName];
               }
             catch (Exception ex)
              {
              //you should save the "ex" somewhere to see its outputs
               ex.ToString();
              }
           }
           newDestItem.Update();  //only now you call update!
        }
       }
      }