Just use a variable. You can put what ever you like as the value, even a name.
Then at runtime if you have three instances named huey, dewey, and lewy to pick on of them just use the compare variable condition.
So if you wanted lewy you would just need to make sure that that value was a used as its variable.
You have two ways to do that.
1:Name it in the editor.
2:Name it when it is created.
The differences between the two was should be fairly obvious.