Since eZ Platform v1.9 the ezplatform:reindex Symfony command re-indexes all Content items after installation (ezplatform:install). Having Legacy Search Engine FullText index data in initial data (a.k.a cleandata) is both redundant and obsolete, since it might be outdated anyway.
Moreover since eZ Platform v2.5.6, the ezplatform:install command accepts --skip-indexing option, so this even could be seen as a bug. The bug is not visible by accident due to changes from
EZP-31299 released in eZ Platform v2.5.9, so there's no point in fixing it in 2.5.next LTS - applies to eZ Platform 3.0 only.