Знаймо українську — difference between по- and попо- prefixes, as in “попоїсти”?

[bytebuster]

Q: Is there any functional difference between по- and попо- prefixes, as in “попоїсти”?

According to the dictionaries, they both denote perfective mood of the verbs:

поїсти vs. попоїсти,
походити vs. попоходити

…and so on.

Do these prefixes have equivalent function, or is there any difference?
If there is any, how do I choose which one to use?