Copying.hst file

[nfountai]

I am confused with this:

This computer has Ver 5.3 Windows 7 external hard drive1
The other laptop is Ver 5.35 Windows 8 external Hard drive2

In order to have the same songlist and song files & etc, to act as a duplicate I copied the entire external hard drive1 to the external hard drive2.
I than copied the files from programdata/mtu.com/Hoster/"all files" from the Ver 5.3 to Ver 5.35. They work just fine when I open them on Ver 5.35.
But I created a new file on the Ver 5.35 and wanted to use it on the Ver 5.3 and the pop up says wrong format ".hst".

This is so crazy as files can go to the newer ver 5.35 but not back to the older ver 5.3?
I tried bringing back a file created on the older Ver 5.3 and copied to the newer Ver 5.35 and than tried bringing it back to Ver 5.3 and wrong format.

Anybody got a clue?