Currently, when adding items to an existing record- the option is to add item, duplicate or add multiple items.  When the option is chosen for adding multiple items, there is a box displayed that a quantity can be entered. If the number is large (above 100) there is a pop-up message confirming this many.  

In addition to the pop-up, it would be helpful for a system preference to set a maximum number for this feature -as it is with Batch Item Modification / Batch Item Deletion.