Hello Shani.
I'm afraid that even if you make the document a double page spread that won't guarantee that the reader will see it as such.
Most PDF readers - in fact, all those I've looked at - allow the user to specify how the pages are displayed. So, whilst most people will probably have an equivalent of "display as document requires" set, some people will have "single page" or something similar as the default. In these cases your double page spread layout will be 'corrupted'. This is the same for in-browser PDF display functionality too.
For example, my Adobe Reader is set to just use the document settings - I keep the installation defaults for final pre-publication checks - but my Preview is set to only display single pages continuous - so I can see what stuff looks like from the "other way round".
Basically there's not much you can do. The user always has the option to override what you want anyway.
Garry.