Recent researchers now guess he started his career as a Lefty and probably became a Switch hitter later. A number of players in those days batted righty against curveball pitchers but not necessarily against all Lefties. BaseballReference changed hm to a Switch, MLB.com still shows him as a Lefty.
https://baseballhall.org/discover/new-evidence-leads-to-switch-in-roger-connors-record