Hi Exotyc,
Yes, I currently have one equipped to Growlithe and one in my inventory. I should have been more specific in my original post.
I have been playing PRO for over a week now and earned a total of (4) Leftovers in my Kanto playthrough so far. Two from Dig Spots, one from hidden item in S.S. Anne, and one from catching Snorlax with Leftovers as a held item. The first time I lost one of the Leftovers after removing it from my Pokémon was before Rock Tunnel, and the second time last night on Route 16.