3rd time reapplicant here (MD only all 3x).
Schools CAN and WILL know if you're a reapplicant. While you don't necessarily disclose this on your AMCAS, almost every secondary I completed either asked a yes or no question if you've applied before. Most asked "if you have applied before, tell us what cycle, and how you've changed your application since then?"
I got in. My biggest hindrance was my MCAT score. I retook it a whopping 3 times, got myself a masters degree, and continued my research throughout this time. In fact, the school I'm accepted at pre-II rejected me my first cycle. I reapplied not my 2nd cycle but my 3rd. I wrote that essay saying "how my application changed." The odds were all stacked against me. AND during the interviews, the interviewers even asked me about all of my prior cycles. I discussed how I was immature when I first applied and was half-assing my application but today, I'm a different man, a man ready to begin his medical education. Low and behold, accepted. 👍