I have a work around for this, its a bit messy but it does work
Lets say you have 2 Picture Libraries in the same site called Photo1 and Photo2
You wish to display them on a page called MyPhotos.aspx
The process is as follows:
- Create a file called HideEverything.css this contains styles to hide all the unwanted elements on a page, basically everything except the Slide Show. Upload this to a regular library.
- Create a web part page called P1.aspx insert the Slideshow Web Part and connect it to Photo1. Add a content editor web part below this and Link it to HideEverything.css
- Create a web part page called P2.aspx insert the Slideshow Web Part and connect it to Photo2. Add a content editor web part below this and Link it to HideEverything.css
- Create a WIKI page called MyPhotos.aspx set the layout too two columns. In the left column insert a page viewer web part and set it to display P1.aspx?IsDlg=2, in the right column insert a page viewer web part and set it to display P2.aspx?IsDlg=2
Your slideshows will now display the correct content on MyPhotos.aspx
I have the styles for hiding the page elements if you need them