I see that as well on both windows and mac.
One way around that is to save your duotone settings as a preset and then record an action loading that preset.
I am still having the same problem in Photoshop CC 2014. When the action is recorded in Photoshop CC the mode change to duotone is always defined as a description of duotone ink and transfer points. Even when loading a duotone preset while recording. We have to go back to Photoshop CS5 to record an action defined as a link to a duotone preset. This is not a tenable solution because our OS will eventually not support CS5.
From what I have seen, when an action with the description of duotone transfer points is played back only the first 5 transfer points are used for each curve. All the transfer points past the fifth are set to null, including 100. Also transfer points that are equal, like Value: 50 - Response: 50, are not recorded at all. That is a big problem because equal value transfer points like that are used along with other transfer points to set the slope of curves. They can't just be ignored.
Here is an example of the actual duotone curve and the results when playing it back from an action. You can see that only the first five transfer points are correct and the rest are set to null, including 100 which is reset to 100.
Hopefully this is a known bug that is being worked on. Can we return to the previous way of recording a duotone mode change as a link to the duotone preset like in Photoshop CS5? That still works when played back in Photoshop CC 2014. Hopefully we can solve this issue soon.