Yes, those repeated entities are from a broken xml lib that constantly duplicates all enties each time the file is loaded into CodeView or BookView.
That incorrect libxml was part of an old installer. See this post from earlier in this thread:
https://www.mobileread.com/forums/sh...1&postcount=10
I know DiapDealer fixed the libxml that was part of Sigil 0.9.12 installer for Windows but I do not know if he also fixed the libxml in the Sigil 0.9.11 release.