Id going into idnumber

[flartet]

Hello,
I have customized your plugin to work differently (I wish I had the time to publish it properly ...)
Still, I think there is a strange possible behaviour in locallib.php:97
$metagroup->idnumber = $group->id;
You're putting the group id of the existing group through the link to the idnumber but it is possible to have multiple link, so the same idnumber.
But, i can get the idnumber must not be unique (that's my case), why not putting idnumber into idnumber to have the same value and a better match between the group and its mirror ?
Thanks !