When closing out Serve or Bluebird to get Redbird, we have previously advised using a different email address and phone number because people used to have issues during registration and billpay...it worked using diff ones. Recently however people are reporting registering successfully using the same phone nr and email address as on the Serve/Bluebird account.
There's no conclusive evidence on this. Also--and this is the root of the problem I think--a few people have reported that the Amex reps have admitted to some recent technical issues in this respect, that is when you close one prepaid Amex account to open another, sometimes it shows still open even when it is not...it seems to work for most people but some have had to wait for a few to several days.
Long story short, use the same email address & phone nr for now, since, inconclusive as it is, it seems to have a better change.
P.S. Do report your data points though about this, it helps others