MIT Digital Currency Initiative researcher James Lovejoy made a post, claiming that the network suffered two deep reorganizations, causing double-spending.
Hours later, at exactly 00:24:08 on Friday, 24 January 2020, another 15 blocks were removed with 16 blocks added. In this second occurrence, a total of 5,267 BTG, roughly $53,000 was double-spent. The second occurrence took three transactions of 1,947 BTG, 1,850 BTG, and 1,470 BTG.
In May 2019, the Bitcoin Cash (BCH) blockchain was also with a 51% attack.