How does search behave when multiple searches are spawned using same session.

Hi I have run in a bug where the tester is automating a test to call search multiple times using the same session, user and request. They are seeing a INTERNAL_SEARCH_ERROR. Imagine I have a httpclient with url and request body setup and I hit the "SEND" button 4 - 5 times continuously. I would imagine this behavior as it would overload the server. But I am hearing different opinions on this though. I am being told that a new search is spawned in novus with each request. I am not quite convinced about this. I would expect that there would be some sort of a shield from robots that could spawn many requests and cause performance issues. Could anybody shed some light on this please. Thanks Venkat