/c^ered/ and /c^ere"d/ are two acceptable spellings of the same word, they don't represent any difference in lexical meaning. It's just the letter /e"/ (jo) is considered necessary in texts for children, while it's avoided in "serious" texts and is substituted to /e/. Two entries in yxo.com most likely appeared because their data base is a compilation of several sources -- some of them used /e"/ and some /e/.