Merge two version of the same databases

I'm supporting a small Lacerte office where we are upgrading the computers from XP to Vista. After installing the new software on Vista, and then transferring the databases, we ran into some major problems with the Vista computer. At that time, the user switched back to the XP without transferring the databases back and worked on the XP machine until we fix the problems with the Vista computer. Now we have two versions of basically the same database but with different set of changes. Is there a way to merge the two database into one that we can use to move forward with?