Compare EPM Document iterations

Is there a simple way to compare 2 version/iteration of an EPM Document/DITA document.

Basically, I want to select 2 dita documents, open them in AE and run a compare.  Or use a diff tool that would be ok too.

Adding an older iteration to the workspace and viewing in Arbortext Editor does not always work - there's a bug. Plus you can't add both, the default is always the current document.