Don't confuse chóngchóng (重重, layer upon layer) with zhòngzhòng (重重, heavily). When pronounced zhòngzhòng, it means 'heavily' as in 重重地摔了一跤 (fell down hard).
usage
Most commonly appears in set phrases like 重重困难 (numerous difficulties), 重重包围 (heavily surrounded), 重重障碍 (many obstacles).
