YOU SAID:
i like potatoes that are potatoes
INTO JAPANESE
私はジャガイモであるジャガイモが好きです
BACK INTO ENGLISH
I like potatoes which are potatoes
INTO JAPANESE
私はジャガイモであるジャガイモが好きです
BACK INTO ENGLISH
I like potatoes which are potatoes
That didn't even make that much sense in English.