I'm not too crazy about same initials. Some names work, but some don't. Take the name you gave as an example,
Peter Parker - I don't think that's works because both in with an "r" sound (it sounds like that nursery rhyme: "
Peter Piper Picked A Pepper..."). But, that my opinion.
Here are some ways same initials work, I think:
Megan MarieJon JosephJoseph Jon