Not sure if this is the proper exchange, but here we go anyway.
The rfc3986 is not entirely obvious about this. Is the following URL considered allowed?
foo://example.com:8042/over/here?name=ferret/over/there?name=possumIt would indicate quite clearly a single resource and could be useful in a RESTful API. A use case would be to delete a part of a resource like one orderline in an order.
A related question asks about a double ?? which is not entirely the same.