I was looking at FR24 for flights in the area this morning and it showed a couple of Alaska Airline flights near each other and within a few hundred feet of each other. Both departed Seattle, one was headed to San Jose (AS318) and the other to Ontario (AS530). Ontario is about 350 miles south of San Jose, but FR24 showed AS530 descending at about the same rate as AS318. After AS318 landed I couldn't find AS530. I went to the Alaskan Airlines website and it showed that the flight had been canceled. I presume this is a glitch and wonder what caused it?