What is the pronunciation of 着重?
Edit: I was born in H.K, I would accept the Hong Kong's standard

/zhuó zhòng/ is the standard reading of 着重

There's a 著 , 着.discussion on this subject here http://www.cantonese.sheik.co.uk/phorum/read.php?14,139780

著 in 衣著 is pronounced /yī zhuó/ 

著 is used in place of 着 in Taiwan

In summary:  

着= /zháo/

着重 = /zhuó zhòng/ (in this compound , 着 is read the same as 著 in 衣著)

著重 = /zhuó zhòng/ (only in Taiwan)

The editor at Pleco might had considered 着 and 著 the same character in this compound (accepted both Taiwan and mainland China's standard),  and listed both single character's pinyin.