Fedora 15 versus 17, files missing on the same filesystem

[Pavel Lisy]

Hello 

I've found strange problem

I have home PC with multiboot instalation of 2 versions of Fedora
distro: F15 and F17. 

There is one ext4 filesystem for data on LVM mounted from both systems 

When I've copied some files to it in F15 I don't see them in F17. 
I've never experienced this on linux. How is it possible?

I can even see different free space in df.
f15/df-h:/dev/mapper/data-music         60G   53G  3,7G  94% /mnt/music
f17/df-h:/dev/mapper/data-music         60G   49G  8,1G  86% /mnt/music

Can somebody help me with it?

Pavel