can a macbook air open a zip file?

Yes. Just double-click on the file to de-archive.

All double clicking did was to duplicate the zip file.

Are you sure that the second one wasn't the unzipped file?

They tend to overlap each other.

The file was unzipped. What happened was that I didn't know where it was. It just didn't unzip and come up on the screen. Thanks

the same to me, only doubled the file