That's what i made.
First i changed in iPad: settings: general: informations: name. No change.
After, i changed like you said, but no change.
I comfirm push token are differents.
There's no problem with an iPhone or android phone : both connect immediatly.
At the begining, the iPads had same name: that's why i renamed them in App settings.
Thanks for answering,
If i delete the IPads in device list of user and add new profile, both IPads connect on the server.
But when i come back later one IPad is deconnected and no possibiliy to reconnect.
I tryed wifi off, plane mode, no difference.
Customer support service by UserEcho