Remove duplicate nodes in a Neos setup with nodes without and with dimensions

dimension_fix.sql

UPDATE neos_contentrepository_domain_model_nodedata SET dimensionvalues = '{
    "language": {
        "0": "de"
    }
}' WHERE dimensionvalues = '{}' and path <> '/' and path <> '/sites';

delete t1 FROM neos_contentrepository_domain_model_nodedata t1
INNER  JOIN neos_contentrepository_domain_model_nodedata t2
WHERE
    t1.lastmodificationdatetime <= t2.lastmodificationdatetime AND
    t1.persistence_object_identifier <> t2.persistence_object_identifier AND
    t1.identifier = t2.identifier AND
    t1.dimensionvalues = t2.dimensionvalues;

Adjust the default dimensionvalue in the first query as needed.
Afterwards run ./flow node:repair to clean the project up.

Thanks for sharing :)