There is "no duplicate penalty" actually GG just ignore that duplicate page

A late conversation with one of our consultant who make 2 duplicate sites , one old and new one said that , there was actually no duplicate penalties , the 2 sites still has SERPs and just one from 2 will be shown on organic search page , the one that has more authority , the one that has easier reach and more traffic , and , sure the other page in other site was hidden in somewhere or ignored.