I updated my local function as follows
using System.Linq;
public static void RenderMetaTag(Page page, string name,
string content, bool overwriteExisting)
{
if (page == null || page.Header == null)
return;
if (content == null)
content = string.Empty;
HtmlMeta control = page.Header.Controls.OfType<HtmlMeta>().FirstOrDefault(meta => string.Equals(meta.Name, name,StringComparison.OrdinalIgnoreCase));
if (control == null)
{
control = new HtmlMeta();
control.Name = name;
control.Content = content;
page.Header.Controls.Add(control);
}
else
{
if (overwriteExisting || String.IsNullOrEmpty(control.Content))
{
control.Content = content;
}
}
}