I had the same problem. I talked about two my activities in my personal statement and reused one as my most meaningful experience and used new activities for remaining two. I think it should be fine as long as what you are saying for your most meaningful experience description adds something new to what you already said in your personal statement. For example, I talked about research in my personal statement for about 2 sentences, but in my meaningful experience box, I talked about it in way more detail. As long as you aren't redundant, I think you are fine!