As far as I can tell, the code isn't set up to do side-by-side bars for a single "x value". But I'm new to maintaining this module, so I welcome any of the other maintainers' comments.

Are you looking for a one-time solution or a solution that you will use repeatedly? If it is a one-time solution, we can talk about hacking the SVG file (i.e. the graph file itself). If it is more of a long-term solution, then we can talk about hacking the source itself (a little more involved, but perhaps resulting in a patch that would be useful to many others as well).

Please let us know a little more of exactly what you need and we'll see how we can help.