YOU SAID:
I have eaten a yellow potato while eating a green potato
INTO JAPANESE
グリーンポテトを食べながらイエローポテトを食べました
BACK INTO ENGLISH
I ate yellow potatoes while eating green potatoes
INTO JAPANESE
グリーンポテトを食べながらイエローポテトを食べました
BACK INTO ENGLISH
I ate yellow potatoes while eating green potatoes
That didn't even make that much sense in English.