My Amiga's Microbotics Starboard RTC didn't account for Leap Day. The truth is, the RTC software stopped working many years ago, but a friend - Chris Brenner - wrote a patch a few years ago that pushed it forward another 30+ years. I feel like I remember Chris saying it wouldn't account for Leap Day, though.
I have to imagine that was a fairly common oversight in early-days computer clock software.