Could not set same user to several "dex"(k8s) clusters

[Zelendar]

Describe the bug
When using several k8s-clusters with configured dex on each of them, could not set unique tokens for each cluster-user

Loginapp & Dex version
loginapp: v3.2.3
dex: v2.25.0

Configuration
scopes:

• openid
• profile
• email
• offline_access
• groups
• audience:server:client_id:"oidc-client"

web:
mainUsernameClaim: email

To Reproduce
Login with dex and apply loginapp generated k8s-config for the first k8s-cluster
we`ll get:

• cluster
• context
• user
  One same host, login to second cluster, using dex+loginapp and get its kubeconfig
  Applying it will:
• cluster (add)
• context (add)
• user (REWRITE previous)
  Now we are not allowed to do anything in first cluster, because user-token is rewrited by second config

Expected behavior
username should optionally contain cluster-name in loginapp html. Like
users:

• name: SomeUser@ClusterName

Additional context
It is very important for people, who use a lot of k8s-contexts on one host. As an example - look the way gangway used to handle with it:
kubeCfgUser := strings.Join([]string{username, cfg.ClusterName}, "@")
...
kubectl config set-credentials "{{ .KubeCfgUser }}"