I am not sure whether this situation is too unusual to worry about fixing, but I figured I should bring it up.
Yesterday I added the PDF for Rituals by Everybody Games for Starfinder into my shopping cart in Internet Explorer.
Later on, I did more shopping in Google Chrome and added more PDFs to my shopping cart. I noticed that the Rituals PDF was not there, so I added it to my shopping cart again. I then completed the purchase and downloaded all of my PDFS.
Still later, I went back to take another look at my shopping cart and found that the Rituals PDF that I had put there earlier in the day had reappeared there, with the indication that I had already purchased it. I was able to remove that item from my cart.