Assume you are referring to the mix of front end frameworks. That does look pretty funny, but the BBC uses different front-end frameworks on different parts of their site - some have been getting rebuilt with new while others were built a while ago.
eg. angular.js is used on the CMS side - Curation Kit, React JS is used on the new BBC Mobile Homepage, and ExtJS is used on their shop - http://shop.bbc.com/us/page/home. Mousing over should reveal some of the notes per technology - I could probably make that info easier to find.
Not just that, but 10+ different ad and analytics providers, and no fewer than five backend languages (PHP, Node, Java, Ruby, Scala). I'm being sort of unfair, as the BBC is a large, diverse organization that has been around for a long time, and I would be surprised if any one person has to deal with all of the listed technologies. It just happened to be the first of several large and redundant "full stacks" listed on an obnoxious-to-navigate site.
eg. angular.js is used on the CMS side - Curation Kit, React JS is used on the new BBC Mobile Homepage, and ExtJS is used on their shop - http://shop.bbc.com/us/page/home. Mousing over should reveal some of the notes per technology - I could probably make that info easier to find.