環 and 睘 don't sound similar in modern Mandarin due to historical phonetic changes. They were more similar
in older Chinese.
Character Evolution
BronzeMid Western Zhou~900 BCBronzeLate Western Zhou~800 BCBronzeLate Western Zhou~800 BCSealWarring States (Chu)475-221 BCSealWarring States (Chu)475-221 BCSealWarring States (Chu)475-221 BCSealShuowen~100 ADClericalQin221-206 BCClericalWestern Han202 BC-9 ADClericalWestern Han202 BC-9 ADClericalWestern Han202 BC-9 ADRegularModern