Adding old posts to a new subdomain on multisite


I've recently transformed a single wordpress install to multisite is currently active. All outside links to it work fine.

I've created the subdomain and used the wordpress importer plugin ( to COPY my posts from the music category there.

So now I have two duplicate posts (in maintenance mode)

So do I have to now cancel all the posts from my original music category on the main site? After which, ... will all the links to posts then automatically redirect to the new subdomain?


Another question
P.S. Any solution to getting thumbnails and media files on the correct place on the subdomain?