Duplicate currency entry with the same ISO code

[ttjiaa]

A recent graphql gem bump PR in Billing which introduced additional checks to ensured a field isn't defined more than once revealed an issue with Money::Currency.currencies as there is a pair of currency entries with the same ISO code.

The error is raised on https://github.com/Shopify/billing/blob/dependabot/bundler/graphql-1.12.4/app/graphql/types/currency_code.rb#L8, when the iso_code is used to create the fields. There are 2 that are the same with GHS, which results in the error ArgumentError: GHS is already defined for CurrencyCode, please remove one of the definitions.:

[19] pry(main)> (::Money::Currency.currencies.values.map{|x| x["iso_code"]}).count
=> 190
[20] pry(main)> (::Money::Currency.currencies.values.map{|x| x["iso_code"]}).uniq.count
=> 189

{
   "priority":100,
   "iso_code":"GHS",
   "name":"Ghanaian Cedi",
   "symbol":"₵",
   "disambiguate_symbol":"GH₵",
   "alternate_symbols":[
      "GH₵"
   ],
   "subunit":"Pesewa",
   "subunit_to_unit":100,
   "symbol_first":true,
   "html_entity":"₵",
   "decimal_mark":".",
   "thousands_separator":",",
   "iso_numeric":"288",
   "smallest_denomination":1
}

{
   "priority":100,
   "iso_code":"GHS",
   "name":"Ghanaian Cedi",
   "symbol":"₵",
   "alternate_symbols":[
      "GH¢",
      "GH₵"
   ],
   "subunit":"Pesewa",
   "subunit_to_unit":100,
   "symbol_first":true,
   "html_entity":"₵",
   "decimal_mark":".",
   "thousands_separator":",",
   "iso_numeric":"936",
   "smallest_denomination":1
}

Based on https://en.wikipedia.org/wiki/ISO_4217#Numeric_codes, it looks like the "iso_numeric":"288" one is historic while "iso_numeric":"936" is current.

I'm unsure how long this has been going on. The relevant ymls haven't been recently changed and they seem to look correct: 288, 936.

Is this indeed an issue? Should we make sure that Money::Currency.currencies doesn't return two currency entries for GHS?