You can not stack 2 of the same buff. So Major Evasion would not stack with Major Evasion. Side note, Majors will stack with Minors.
I prefer Deadly Cloak, especially if you are running a set that procs off of physical damage. For instance, Berserking Warrior works perfectly with Deadly Cloak. As for Mirage, I don't see a reason to run it in PVE.
I think it's more comparable to put Nightblade Mirage against medium armor's Shuffle. Both give Major Evasion for at least 20 seconds, and can remove snares and such.
Then the difference is clearer. Primarily a magicka vs. stamina concern, but Mirage gives more tankiness.
Dual Wield skill Deadly Cloak also gives the Major Evasion part but I consider its Major Evasion as "bonus".
If you're using Deadly Cloak anyway for the damage, then you likely don't need to slot Mirage (or Shuffle).
If you're using Deadly Cloak pretty exclusively for the Major Evasion (in highly mobile fights where you can't stack and stand on top of targets) it becomes just a short and more annoying option vs. one of the others.