I looked at the team pages. Unfortunately it doesn't give stats for pitcher's pinch hitting (I guess that's a reasonable omission!).
But it does show that Duke had 45 plate appearances. He appeared in 50 games as a pitcher - 18 as a started and 32 in relief. It's worth noting that he was probably used primarily as a lefty specialist in his relief appearances, so he probably didn't have many at bats as a reliever. If he had 2 plate appearances per game as a starter, that would be 36. If he had maybe 4 more plate appearance as a reliever, that would suggest approximately 5 at bats as a pinch hitter.
Like I said, I can vouch that it did happen against me. In emails with the manager, he confirmed that this was a planned strategy on his part - that HAL would choose to use Duke as a pinch hitter.
You could PM the manager if you want to discuss it with him some more, or ask him to post his thoughts here. His user name is MichaelRobb11 . He's a very cagey (good!) manager, by the way!!!