Direct your naysayer to the definition of an electronic funds transfer error in Reg E 1005.11(a)
Definition of error. (1) Types of transfers or inquiries covered. The term "error" means:
(i) An unauthorized electronic fund transfer;
(ii) An incorrect electronic fund transfer to or from the consumer's account;
(iii) The omission of an electronic fund transfer from a periodic statement;
(iv) A computational or bookkeeping error made by the financial institution relating to an electronic fund transfer;
(v) The consumer's receipt of an incorrect amount of money from an electronic terminal;
(vi) An electronic fund transfer not identified in accordance with § 1005.9 or § 1005.10(a); or
(vii) The consumer's request for documentation required by § 1005.9 or § 1005.10(a) or for additional information or clarification concerning an electronic fund transfer, including a request the consumer makes to determine whether an error exists under paragraphs (a)(1)(i) through (vi) of this section.
A duplicate charge is an "incorrect electronic funds transfer to or from a customer's account." Reg E covers a lot more than just fraudulent transactions.