For good interoperability, metabolite DataNode
identifiers map to a single InChIKey.
Mapping to more than on InChIKey original from a possible problem in the BridgeDb metabolite
identifier mapping database, copied from the sources it used (currently HMDB, ChEBI, and Wikidata).
The used identifier maps to more than one InChIKey. This does not mean the used identifier is wrong itself.
You can either report the problem in this BridgeDb tracker or see of the problem originates from Wikidata.