Through my findings I have and ancestor Pietro Catinella who was born 1803-1805 and married a Maria Amenta in 1828. I have a death document for a Antonina Germano aged 50 years old who died in 1858 and her husband appears to be Pietro Catinella in which they were married in 1829. I know it could be a common name but I'm thinking maybe Maria Amenta died shortly after her and Pietro's marriage (1828-1829) and if Pietro is the widower then possibly he could be the same Pietro who married Antonina Germano (also an ancestor) in 1829.
That's why I'm wondering if "Vedova di pietro" means pietro was married before.
One way to tell if it's the same Pietro is to look at both marriage certificates and after his name should be his fathers first name and also his mothers name. If these are the same on both documents than Pietro would be the same person in each.
Hope this might help to clarify the two documents for you. I'll be interested to find out if he is one in the same. Post back and let us know.