It looks like you're referencing a potential update range for Red Dead Redemption 2 on PC or console, specifically from build 1311.23 to 1491.50. However, based on official Rockstar game version history, there is no widely documented jump from 1311.23 to 1491.50 in a single patch.
The update 1311.23 - 1491.50 is available for download on all platforms. Players can access the update by: Red Dead Redemption 2 update 1311.23 - 1491.50 ...
The Evolution of Red Dead Redemption 2: A Look into Update 1311.23 - 1491.50 It looks like you're referencing a potential update
Red Dead Redemption 2 Update 1311.23 - 1491.50: A Comprehensive Guide to the Latest Patch Content: Red Dead Redemption 2 Update 1311