I hate it because it's one of those cutsey twin names. I know a family with twins named
Christopher and
Christian, so even if the parents knew
John and
Jack were the same name, they still may have chosen it. People seem to think that twins need twin names. I have no idea why.
I know
Jack now is a popular given name, but for people in older generations,
Jack is only a nickname for
John, not a proper given name. I much prefer
John nn
Jack, and I bet that will become more popular considering how trendy
Jack and
Jackson are.