'selectFiles' Not working when calling twice

[Raphael Nunes dos Santos]

When i try to use the selectFiles helper twice in the same input this erro ocour:
TypeError: Cannot redefine property: files at Function.defineProperty (<anonymous>) at buildFileEvent (fire-event.js:190) at fireEvent (fire-event.js:50) ...

[Raphael Nunes dos Santos]

I was able to fix the problem just addin the files attribute before calling the selectFiles helper, but adding the configurable option to allow the attribute to be changed.
Object.defineProperty(find(${selector} [data-test-input-file]), 'files', { value: {}, configurable: true });

[Andrew Kirwin]

I was also experiencing this with @ember/test-helpers
emberjs/ember-test-helpers#326