Duplicate paths and keys cause an error to be reported in terms of into-hash, but it would probably be better to report it in terms of syntax-property-bundle. These example docs reveal the problem:

The other syntax property bundle construction functions probably have the same issue.
Duplicate paths and keys cause an error to be reported in terms of
into-hash, but it would probably be better to report it in terms ofsyntax-property-bundle. These example docs reveal the problem:The other syntax property bundle construction functions probably have the same issue.