there has been a few times that I stared a song and then found out that i had to stop midsong. So I know theres a way to mark a song as played but not the other way around.
Create a new folder in the main songs folder to put such songs in while in-game or just write them down. I personally keep a text file handy on my desktop for songs that I really like but haven't gotten to full combo, or have a low ranking on and such.
Well, at least you tried this time. (Took me a few minutes to find the topic as well, and it wasn't the duplicate I was even looking for [i.e., there's more])