In my case, a couple of my PRs are decently far from my second-best time at that distance.
I'll give ONE example, it's my very worst PR, and my worst second effort. Yes, I know I sucked as a marathoner, so no need to tell me.
Marathon (I've run 7 of them, but only actually tried to do well in 3 of them; 2 of those 3 are listed below):
2:55 PR
3:20 second best time (HUGE bonk here...went through the half in 1:20 and then took 2 hours (mostly a very bad last 5 miles) to do the second half.
Got stuff like that?