citation, homepage, and license fields of `dataset_info.json` are duplicated many times
{'login': 'samsontmr', 'id': 15007950, 'node_id': 'MDQ6VXNlcjE1MDA3OTUw', 'avatar_url': 'https://avatars.githubusercontent.com/u/15007950?v=4', 'gravatar_id': '', 'url': 'https://api.github.com/users/samsontmr', 'html_url': 'https://github.com/samsontmr', 'followers_url': 'https://api.github.com/users/samsontmr/followers', 'following_url': 'https://api.github.com/users/samsontmr/following{/other_user}', 'gists_url': 'https://api.github.com/users/samsontmr/gists{/gist_id}', 'starred_url': 'https://api.github.com/users/samsontmr/starred{/owner}{/repo}', 'subscriptions_url': 'https://api.github.com/users/samsontmr/subscriptions', 'organizations_url': 'https://api.github.com/users/samsontmr/orgs', 'repos_url': 'https://api.github.com/users/samsontmr/repos', 'events_url': 'https://api.github.com/users/samsontmr/events{/privacy}', 'received_events_url': 'https://api.github.com/users/samsontmr/received_events', 'type': 'User', 'site_admin': False}
[{'id': 1935892871, 'node_id': 'MDU6TGFiZWwxOTM1ODkyODcx', 'url': 'https://api.github.com/repos/huggingface/datasets/labels/enhancement', 'name': 'enhancement', 'color': 'a2eeef', 'default': True, 'description': 'New feature or request'}, {'id': 1935892877, 'node_id': 'MDU6TGFiZWwxOTM1ODkyODc3', 'url': 'https://api.github.com/repos/huggingface/datasets/labels/good%20first%20issue', 'name': 'good first issue', 'color': '7057ff', 'default': True, 'description': 'Good for newcomers'}]
[]
Thanks for reporting :)
Maybe we can concatenate fields only if they are different.

Currently this is done here:

https://github.com/huggingface/nlp/blob/349ac4398a3bcae6356f14c5754483383a60e8a4/src/datasets/info.py#L180-L196

This can be a good first contribution to the library.
Please comment if you'd like to improve this and open a PR :)
This happens after a `map` operation when `num_proc` is set to `>1`. I tested this by cleaning up the json before running the `map` op on the dataset so it's unlikely it's coming from an earlier concatenation.

Example result:
```
"citation": "@ONLINE {wikidump,\n    author = {Wikimedia Foundation},\n    title  = {Wikimedia Downloads},\n    url    = {https://dumps.wikimedia.org}\n}\n\n@ONLINE {wikidump,\n    author = {Wikimedia Foundation},\n    title  = {Wikimedia Downloads},\n    url    = {https://dumps.wikimedia.org}\n}\n\n@ONLINE {wikidump,\n    author = {Wikimedia Foundation},\n    title  = {Wikimedia Downloads},\n    url    = {https://dumps.wikimedia.org}\n}\n\n@ONLINE {wikidump,\n    author = {Wikimedia Foundation},\n    title  = {Wikimedia Downloads},\n    url    = {https://dumps.wikimedia.org}\n}\n\n@ONLINE {wikidump,\n    author = {Wikimedia Foundation},\n    title  = {Wikimedia Downloads},\n    url    = {https://dumps.wikimedia.org}\n}\n\n@ONLINE {wikidump,\n    author = {Wikimedia Foundation},\n    title  = {Wikimedia Downloads},\n    url    = {https://dumps.wikimedia.org}\n}\n\n@ONLINE {wikidump,\n    author = {Wikimedia Foundation},\n    title  = {Wikimedia Downloads},\n    url    = {https://dumps.wikimedia.org}\n}\n\n@ONLINE {wikidump,\n    author = {Wikimedia Foundation},\n    title  = {Wikimedia Downloads},\n    url    = {https://dumps.wikimedia.org}\n}\n\n@ONLINE {wikidump,\n    author = {Wikimedia Foundation},\n    title  = {Wikimedia Downloads},\n    url    = {https://dumps.wikimedia.org}\n}\n\n@ONLINE {wikidump,\n    author = {Wikimedia Foundation},\n    title  = {Wikimedia Downloads},\n    url    = {https://dumps.wikimedia.org}\n}\n\n@ONLINE {wikidump,\n    author = {Wikimedia Foundation},\n    title  = {Wikimedia Downloads},\n    url    = {https://dumps.wikimedia.org}\n}\n\n@ONLINE {wikidump,\n    author = {Wikimedia Foundation},\n    title  = {Wikimedia Downloads},\n
```

@lhoestq and I believe this is happening due to the fields being concatenated `num_proc` times.
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