Unfortunately, in version 5 and previous versions of the mSecure app, there is no way to merge data in any simple way. The backup restore process will simply overwrite all data currently stored in the app when a restore takes place. In mSecure 6, we have implemented a merge feature for restoring data, but that version is just about ready for it's first beta release, so it will be at least a couple of months before it's released to the public.
I love your product. Unfortunately, I have been running two versions on my iPhone. Is there any way to merge the files? I am guessing no because like an idiot I have been using both and some data is newer in the different versions.