Multiuser plugin, creating unnecessary identities even i have not requested this

### Step 1: Please describe your environment

* ZeroNet version: 4473
* Operating system: W10 and Raspbian
* Web browser: FF
* Special configuration: Multiuser plugin

### Step 2: Describe the problem:

I think Multiuser plugin is creating identities that i have not requested. In my users.json file i found 3222 times phrase: "master_seed": "
On my new ZN instance, i found it 9 times and the "Change account:" prompt on ZeroHello shows only 6 accounts to choose from.
The /Stats page does not show any information about the users.json content so i can see which identity has how many sites, made how many posts or such. Or even the button to delete the identity - but that would be better for some identity manager/switcher GUI - current identity switcher not good when you have many identities - you can not see it on one page and search thru it.

Can the plugin be fixed so it does not create unnecessary identities at the first place?

I am asking because i was bothered with unreliability of the Multiuser plugin (it changing my identity from time to time) so i disabled it (just by renaming its directory) on my new instance where is 9 identities, but Zeronet was not starting without any indication in the log files. So i guess i have to somehow manually edit the users.json file and discover which identity to leave, but i do not remember where i posted or such to pick right identity "block" to leave.

Commencez par reproduire le comportement du plugin Multiuser et examiner users.json ainsi que l’invite Change account, la page /Stats et les journaux de démarrage. Déterminez pourquoi des identités sont créées ou sélectionnées de manière inattendue, puis vérifiez que la désactivation du plugin et la gestion des identités existantes n’empêchent plus le démarrage et ne masquent plus les informations du compte.

Rédigé par le modèle d'indexation à partir du texte de l'issue.