I experienced the same issue where my action was triggering twice for each button press. I looked at the StakOBot project and noticed that for jumping, it uses ‘started’ rather than ‘triggered’, so I did the same and it fixed my problem. (the brief explanations of the different trigger events should have helped, but like so many of the engine comments it only confused me futher.)
So far my experience with Enhanced Input has not been a positive one. Such a complex, arcane system needs some proper explanation and comprehensive tutorials. The old system was so simple and I wish I had stuck with it, although considering it is deprecated I assume they will remove it from the engine sooner or later. On the plus side, I think I’ve finally got everything working as intended, after many days of working to migrate to the new system.