Routes are unique based on the route method + path. In the above example this route would resolve to be the same as the built-in update function. The Profound.js web service registration program will only register the 1st occurrence of this route, any other duplicates will be logged as errors. This uniqueness rule is across the board for all DbDefn module, all of them need to be unique.
There are a few very simple ways to work around this:
Change the path to be more distinct --> changeQuantity: "/orderdetails/:order/:line/updqty"
See next way to define a route which allow you to define the route method