the name doesn't change. if you used Create Object to make an instance of Enemy, then its name is still Enemy.
if there are other instances of Enemy, then you have to be careful how you "pick" them, otherwise any actions you do may apply to all instances - not just the one you expected.
you can use instance variables to distinguish between them, or their UID, or Enemy(0).x or events such as Is Overlapping...
in your example, you could use the "Self" reference, so it would be:
Object(0) Set X to self.x + 5
Object(1) Set X to self.x + 2
without the self reference you could also say:
Object(4) Set Y to Object(4).Y + 1