Yes you can. All of your Grouped Items are stored in your Documents > Fusion folder by default; you can either find this folder using Windows Explorer, or perform a search for files with a file extension of .GPU and then open the file location.
When copying from/to this folder, please ensure that Fusion is not running at the time and ensure that the files are copied to exactly the same folder location on the target PC.
Note: a .GPU file will be present for each Item Group created within Fusion, with the same file name as provided within Fusion itself.