They're produced in a seperate area of the anus and should be eaten directly from there. It contains vital re-processed nutrients and minerals and if ever you notice the guy NOT eating them then its a problem...
**** Im only going on information for bunnies... If its the same as the cecal feces from bunnies?
It's perfectly normal for a guinea pig to eat it's own droppings. Below is a little bit about coprophagy from a website called Guinea Lynx (http://www.guinealynx.info/), possibly the best website for guinea pig health queries
"Coprophagy (eating the soft cecal feces) is vital to the good health of all cavies as it provides them with necessary nutrients. Cavies may eat the soft cecal feces 150 to 200 times in a day, usually directly from the anus. If an animal is obese or pregnant, these soft droppings may be expelled and eaten from the floor. Very young cavies may also eat their mother's soft droppings. Some cavies have been known to snatch cecal feces from other pigs. These feces are supposedly the best ones to feed a sick guinea pig on antibiotics in order to reinoculate good bacteria into the digestive system. The drier fecal pellets are also used but do not contain as many beneficial bacteria."