I was watching KBOS https://www.flightaware.com/live/airport/KBOS on Thursday morning and saw a couple of Cape Air flights that looked like they were within 500 feet of each other. I suspect we'll be hearing more of these stories soon.
FWIW, the KBOS incident I saw didn't seem to be ATC either, if it was actually what I thought it was. It does seem like either of them may have been caught earlier if there had been more ATCs on staff or if they weren't as stressed or sleep deprived.