I'm the same with near coincidences; the only thing about them is no one knows if they've actually occurred. This is a minor point; the possibilities of near, missed coincidences is endless, though completely pointless even contemplating.
It could be an old friend you haven't seen for twenty years; let's say he's Australian. One year he visits your home country, the UK. He doesn't get in touch because he lost your details years ago; maybe he doesn't even know your surname (maybe he doesn't want to get in touch; let's imagine it's the days before Facebook). Anyway. So. You brush past each other at Waterloo Station and don't even notice. And never do. Never will.
Or it could be someone you've lived with for years; turns out you have a mutual friend you'll never know about. Or you were both at the same wedding in 2003 (you didn't meet until 2011). Or you were both in Shoreditch one sunny day in June 1997. Whatever.
There are probably hundreds of such near coincidences with everyone we know; it's just impossible to find out all of them, and mostly irrelevant too. I found out some with an ex-work colleague recently: we both went to the same art college at the same time, lived in the same seaside town at the same time; a film-maker friend of his was born in a small town I used to live near – his mother has recently moved there... and so on.
Actual coincidences are often amazing and head-spinning but near or missed coincidences are overlooked as they're not known about. But they're out there all the time. Nearly.