Katalon Studio to upload more than one file to same input field

There is file input field on page, where should be attached more than one file at the same time.

I try to use [WebUI] Upload File, but it is unable to handle two files simultaneously.

WebUI.uploadFile(findTestObject('Object Repository/validateFile/input_originalFile'), (d_directory.toString() + '\\') + file1, (d_directory.toString() + '\\') + file2)