Plenty of sites have generic layouts that are clearly "inspired" by other sites. But blatantly re-purposing an entire site's code goes too far. You are right to

Plenty of sites have generic layouts that are clearly "inspired" by other sites. But blatantly re-purposing an entire site's code goes too far. You are right to call them out. Will this fiasco harm your business? Probably not. If anything, enjoy the extra boost in traffic and sales.