Strange xxx-lyxformat-474.lyx files

[Påvel Nicklasson]

I work on several projects in LyX. Lately I have noticed that in the same
folders as my .lyx files there is a second file called -lyxformat-474.lyx.
For instance, if the regular file is called xxx.lyx. The second is called
xxx-lyxformat-474.lyx. The 474.lyx files seems to be old versions of the
regular files.
I have no idea how och when the 474 files were created, certainly not by
me. The only major tampering I have done lately is upgrading to LyX 2.2. I
am on *Buntu 16.04 with LyX stable ppa added. Does anyone know what he 474
files are, and if it is OK to delete them?