C# Add two HTTPS bindings with two different certificate with the ServerManager not working

I am trying to create two different bindings on two different site on IIS with C# from my website. Those 2 binding needs to be set with a certificate (one specific for each bindings). The problem is, the bindings are correctly created but the two bindings are created with the same certificate.

Here my code :

public async Task AddBindings(string code)
{
    await AddBinding("Website1", "website1.com");
    await AddBinding("Website2", "website2.com");
}

private async Task AddBinding(string siteName, string urlDomain)
{
    using (ServerManager serverMgr = new ServerManager())
    {
        var site = serverMgr.Sites[siteName];

        var certif = GetCertificate("*." + urlDomain);
        site.Bindings.Add("*:443:" + urlDomain, certif.GetCertHash(), "My");

        serverMgr.CommitChanges();

        serverMgr.Dispose();
    }
}

private X509Certificate2 GetCertificate(string nameStartWith)
{
    var store = new X509Store(StoreName.My, StoreLocation.LocalMachine);
    store.Open(OpenFlags.OpenExistingOnly);

    X509Certificate2 certif = null;

    foreach (var certificate in store.Certificates)
    {
        var certifDate = DateTime.Parse(certificate.GetEffectiveDateString());
        if (certificate.FriendlyName.StartsWith(nameStartWith))
        {
            certif = certificate;
        }
    }

    store.Close();

    return certif;
}

The "funny things" in the function AddBindings, in this order the two bindings are going to be created with the Website2 certificate, and if I change the order of the two rows it's going to use Website1.

Thank you very much for your helps !