ASP.NET Why doesn't the handler specified in the page markup fire when a page is duplicated?

Question

ASP.NET

There is an aspx page, the tag is specified in it <audio>, and as <source>the ashx handler. In this handler, I receive some sequence of bytes (in my case, this is music), and display it on the page

context.Response.OutputStream.Write(buffer, offset, lengthRead)

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When I launch the application, the music on the page plays, but when I duplicate the tab, everything is silent. Tell me, please, what is the problem here?