Yes. This is sometimes known as an "exploit pool collision". There's a good (long) report from RAND from a couple of years ago on 0-days which discusses government 0-day hoarding at length, including disclosure strategies.
The value of an unpublished 0-day drops as more hoarders discover it (or learn about it through leaks, purchase it on the exploit market, etc). Eventually there's more value in getting it fixed.