foreign_key is for the columns in the database but you also need to make sure the keys in the schema struct are unique. so instead of:
schema "accounts" do
belongs_to :user, User, foreign_key: :all_user_accounts_id
belongs_to :user, User, foreign_key: :selected_user_account_id
end
you need to do something like this
schema "accounts" do
belongs_to :all_user, User, foreign_key: :all_user_accounts_id
belongs_to :selected_user, User, foreign_key: :selected_user_account_id
end