Get back to stable version

HI,

To downgrade, just download WordPress again and delete then replace your copies of everything except the wp-config.php file and the /wp-content/ directory with the new files you just downloaded. That should get you back to the stable release, although do make a backup first as it’s not always possible to downgrade (we do make database changes etc with new versions etc).

I downgraded locally from 4.2 Alpha to 4.1.1 copying the above files.
It asked me to upgrade the database and the message after that was:

WordPress database error: [Duplicate key name ‘meta_key’]

ALTER TABLE wp_usermeta ADD KEY meta_key (meta_key)

WordPress database error: [Duplicate key name ‘slug’]
ALTER TABLE wp_terms ADD KEY slug (slug)

WordPress database error: [Duplicate key name ‘name’]
ALTER TABLE wp_terms ADD KEY name (name)

WordPress database error: [Duplicate key name ‘meta_key’]
ALTER TABLE wp_commentmeta ADD KEY meta_key (meta_key)

WordPress database error: [Duplicate key name ‘meta_key’]
ALTER TABLE wp_postmeta ADD KEY meta_key (meta_key)

WordPress database error: [Duplicate key name ‘post_name’]
ALTER TABLE wp_posts ADD KEY post_name (post_name)

and after that “the update completed” and “the database was upgraded sucessfully” (maybe not exact translation – was in Greek.

Everything seems to work fine. Is it safe to do this on server and keep it like this?
Thanks in advance