People above already correctly broke down the whole thing with apophenia and selective attention, and honestly, they nailed it. I'll just add from my own experience: the exact same thing happens when you buy a bicycle of a certain model and suddenly start noticing that same model everywhere on the streets. It was there just as much before, your brain just filters it out and highlights it now. It's exactly the same with numbers - the moment you notice 11:11 once and think "that's interesting," your brain automatically starts tracking it, and random coincidences get perceived as a pattern.
Here's what's actually happening: you look at the time like 50-100 times a day, dozens of cars pass by, you check receipts. Statistically, repeating numbers will pop up simply because there aren't that many combinations. But you only notice the ones that seem significant, and you just skip the other 99% of coincidences. It's how your brain normally works, nothing mystical about it.
Honestly, this whole thing only starts feeling creepy because you got fixated on it. Try deliberately stop paying attention to it - and after a week you'll notice it seems way less frequent. Or go the other way, start tracking different numbers: go catch all the 13:13 and 17:17. You'll quickly figure out they pop up just as often, you just weren't paying attention to them before.