Godparent or sponsor entries

I've read that if a godparent or sponsor reappears in baptism records for a couple's subsequent child, then the first child for whom the godparent t or sponsor was named died. The explanation given is that the godparent is given a subsequent chance to serve as a godparent. I wonder if this was strictly followed, especially during the famine years when the availability of a sibling or sibling-in-law to serve as a godparent was an issue. I ask this due to a couple of observations regarding records relating to my wife's great-great-great grandmother. First, the most likely candidate for her based on birthdate, townkand, etc,, had a godparent who also was listed as a godparent for her brother born two years later. Second, a couple I believe are her uncle and aunt had 11 children (between 1844 and 1865) but all but 2 had a godparent who was listed as a godparent for a previously born sibling (including the last born child). Does this necessarily mean that 9 of the children died and only 1 or 2 survived? Thanks for Abe replies?