Currently, you can't. If you really want to do this, you can file a Bug Report with Apple.
I would advise against doing this. It's really bad practice, simply because having two different variables named the exact same thing, the only difference being how they are accessed, is a terrible code smell. And it's confusing.
So file a radar if you want to, and then change your variable names. I doubt Apple will "fix" this.
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