Quoting reply by Bitergia's Valerio:

<tl;dr>: Author_org_name stores the same info of author_org_name. The latter are used in the current visualizations and are the ones that should be used to build new visualizations.
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During the enrichment phase of a git commit, the Git enricher collects identities data about the author (stored in the Perceval Author field) and committer (stored in the Perceval Commit field) [1]. For each of these roles, ELK asks SortingHat for data about the corresponding profiles and adds their values to enriched fields with the following structure <role>_username, <role>_email, <role>_org_name, etc. Thus, the enriched item will contain fields like Author_org_name and Commit_org_name. Furthermore, since the attribute Author is also defined as the author of the commit [2], ELK will include enriched fields with the following structure author_username, author_name, author_email, ... and author_org_name. These fields contain the same information of Author_username, Author_name, etc.

[1] https://github.com/chaoss/grimoirelab-elk/blob/master/grimoire_elk/enriched/git.py#L92

[2] https://github.com/chaoss/grimoirelab-elk/blob/master/grimoire_elk/enriched/git.py#L119

It's not a bug and there is no plan to remove them ATM.

This is now also covered in https://gitlab.com/Bitergia/c/FAQ