Most likely, it's just a coincidence, even though it feels mystical. You live in a city with millions of people, but at the same time you follow the same routes - to work, to one neighborhood, to your usual shops and cafes. The guy probably also lives or works nearby and uses the same places. When your brain notices such a pattern, it starts seeing a connection everywhere - it's called pareidolia, but for coincidences. You've simply started noticing his appearance because you already know what he looks like, and he's just living his normal life with no idea that you keep running into each other.
To be honest, I've dealt with this - I was convinced that someone from my neighborhood was stalking me until I realized we just take the metro at the same time and in the same direction. After that, the coincidences stopped feeling like signs of fate. If you really want to understand what this means, try talking to him - just go up and tell him you see him often. Either you'll find out that he's noticed the coincidences too, or you'll realize it's his first time meeting you. But waiting for signs isn't the most productive approach. Fate, if you believe in that sort of thing, usually requires active action, not just coincidences.