In certain cases, Insync may create duplicate files and folders during initialization, if you have chosen to reuse a previous Google Drive or Insync folder.
For duplicated items, in most cases, the originals are the ones suffixed with (2) in Finder. This is because Insync uploads the local one first, then downloads the one from Google Drive.
You may either browse through your files using Google Drive web, or alternatively, use Finder to look for these duplicates as follows.
1. Open your Insync folder in Finder, and start a search by typing (without the quotes) "(2)" in the search box. Click on the folder name (next to "This Mac") to search only the Insync folder and not your entire Mac.
2. Choose to search for filenames matching (2), as in the screenshot below: