Install single SSH key multiple times on single machine via puppet

I want to have one place where I have defined ssh keys for my users. These users can be in different (multiple) roles on single server. So I defined ssh_authorized_key as virtual and then wanted to realize them in different roles. Example:

@ssh_authorized_key {
    "user_a":
        tag     => ['deployer', 'developer', 'root'],
        key     => "xxx",
        type    => "ssh-dss",
        ensure  => present;
    "user_b":
        tag     => ['deployer', 'root'],
        key     => "yyy",
        type    => "ssh-dss",
        ensure  => present;
    "user_c":
        tag      => ['root', 'deployer'],
        key      => 'zzz',
        type => "ssh-rsa",
        ensure   => present;
}

And then realize them for multiple users on single node:

Ssh_authorized_key<| tag == 'root' |> {
    user    => 'root'
}

Ssh_authorized_key<| tag == 'deployer' |> {
    user    => 'deployer'
}

But puppet will install the certificates only for one user. I think that main concept of my solution is wrong. But I can't figure out how to install single certificate to multiple users?