Normally in my experience it would be the most restrictive one gets applied.
I personally really wouldn't do that though. I would ensure only one Energy saver policy goes to each machine, you can sometimes get some strange results, and if there is an issue you have to figure out which policy is causing it.

It depends on what the developer decides. Apple usually takes the most restrictive settings among all the configurations, but others like Google will GIGO multiple configuration profiles targeting the same domain. Generally speaking you do not want to target one key with multiple profiles. 

@tcandela Apple's position in the past on which profile wins has been ¯\\_(ツ)_/¯ . It definitely isn't most restrictive based on the misadventures of many Mac admins who unintentionally deployed more than one profile with Software Update deferrals due to the lack of granularity when configuring a Restrictions payload in Jamf Pro.

Apple's official stance on conflicting configuration profiles is that it is "Undefined."  It may behave one way on one machine but differently on some other machine.  They strongly recommend against conflicting configurations.

Beat me to it. In my last class with our instructor Lee, he reiterated the same thing. 

If you have the same keys in multiple profiles, the outcome is undefined. I have witnessed this myself for macOS and iOS. It is not pleasant experience for admins.