Way to reproduce:

1. create a filter and a sub-filter
2. Right-click on the filter or sub-filter and select 'Duplicate'

Only the top filter is duplicated.

Imported from Launchpad using lp2gh.

• date created: 2011-05-30T08:17:48Z
• owner: sebastien.heymann
• the launchpad url was https://bugs.launchpad.net/bugs/790119