Memory editing programs, such as Cheat Engine, allow you to tinker with the inner workings of a game. For example, using the program with Dishonored 2 can allow you to unlock Emily's powers for Corvo or vice-versa, something that's not currently possible without the extra tinkering. However, when testing out Emily's Doppleganger power as Corvo, Reddit user Lambac0re discovered that Corvo has his own unique Doppleganger model.
Lambac0re shared a picture of both his Corvo doppleganger (above) and his power-selection wheel (below), which looks snug with all of the powers unlocked but not unusable. Another user, ComradePoolio, looked a little closer at the stealth game's Powers menu and noticed that every Emily ability has an appropriate illustration that features Corvo. User JohnKnobody also pointed out that "all of Corvo's powers have Emily-specific illustrations, too."
While it seems like developer Arkane could enable the use of both characters' powers at the same time in a more official manner, we have no reason to believe this will actually happen. In an interview with Game Informer, co-creative director Harvey Smith said the studio "went through many permutations of how [it] grouped or did not group the powers." One of these "permutations" may be seen in the original reveal trailer, in which we saw Emily use Bend Time, a power that's only available to Corvo in the final game.
Regardless, we've contacted publisher Bethesda to ask if Arkane Studios has a plan in place to allow both characters to use all the powers in the future. We'll report back as we receive more information.
If you're interested in using one character's powers with the other, Lambac0re provided an easy "how-to" on how to install and use Cheat Engine. It's always important to practice caution when downloading anything from the internet and remember to back up your save files before modifying anything.