How do I turn off the add to cart message from Commerce site using Rules I finally got a duplicate cart rule to work in my Drupal Commerce site.  My "After item is added to cart" rule determines if there are duplicate sku's, if so, resets the quantity of that item to one.  

When that rule is run, it posts a system message to the user saying the duplicate has been removed from the cart, but the original "Item has been added" message still appears, so the green, "item added to cart" msg appears and just under it, my "duplicate item has been removed" msg appears.  

I want to turn off/not display that first "item has been add" message, when a duplicate has been detected.  Obviously the message would appear as normal when no duplication is found.

What is the simplest means of accomplishing this? Nothing I've tried thus far has worked. 

default add to cart message:

{ "commerce_cart_add_to_cart_message" : {
    "LABEL" : "Display an Add to Cart message",
    "PLUGIN" : "reaction rule",
    "OWNER" : "rules",
    "TAGS" : [ "Commerce Cart" ],
    "REQUIRES" : [ "commerce_cart" ],
    "ON" : { "commerce_cart_product_add" : [] },
    "DO" : [
      { "commerce_cart_add_to_cart_message" : { "commerce_product" : [ "commerce-product" ] } }
    ]
  }
} 


my stop duplicate rule

{ "rules_restrict_quantity_1" : {
    "LABEL" : "Restrict quantity to 1",
    "PLUGIN" : "reaction rule",
    "OWNER" : "rules",
    "REQUIRES" : [ "rules", "commerce_cart" ],
    "ON" : { "commerce_cart_product_add" : [] },
    "IF" : [
      { "data_is" : {
          "data" : [ "commerce-line-item:quantity" ],
          "op" : "\u003E",
          "value" : "1"
        }
      }
    ],
    "DO" : [
      { "data_set" : { "data" : [ "commerce-line-item:quantity" ], "value" : "1" } },
      { "entity_save" : { "data" : [ "commerce-line-item:order" ] } },
      { "drupal_message" : {
          "message" : "Duplicates items are not allow.  This item has been removed from \u003Ca href=\u0022\/cart\u0022\u003Eyour cart?\u003E",
          "type" : "warning"
        }
      }
    ]
  }
}
You can't remove a message from the queue once it's been added via Rules, so you just need to reproduce the conditions in inverse from one rule to the next. In other words, you already configured the conditions in your custom rule to prevent the duplicate, so now put the opposite conditions on the rule that shows the normal Add to Cart message.