<a href got replaced and replicated over and over, CKedit 4.4.1 on MediaWiki

I have installed CKeditor on MediaWiki on my website, looks pretty good,

However, the "<a href" link got replicated over and over on button "save", "preview" or "Show changes",

and the "<code> </code>" tag is also wrong in codesnippet plugin.

I'm totally fresh on PHP and java. What should I do?

Here is changes after twice click on button "Show changes".