It has only ever happened twice in the IRL version of the MLB - on September 17, 1920 (Bobby Veach and George Burns) and September 1, 2008 (Stephen Drew and Adrián Beltré) - and this is the first time it has happened in this timeline, which I guess makes it something of a big deal.
Both Charlie Lau of the Yankees and Philly's Tommy Helms hit for the cycle today, which in game time is August 11, 1965.
History, folks.