Currencies can also contain optional grouping, decimal data, and pattern elements. This data is inherited from the in the same locale data (if not present in the chain up to root), so only the differing data will be present. See the main document Section 4.1 Multiple Inheritance.
Ref: similar issue than reported in https://github.com/tc39/ecma402/issues/241
UTS#35 says:
Example: https://github.com/unicode-cldr/cldr-numbers-full/blob/master/main/pt-PT/currencies.json#L1303-L1310