How to add multiple metaentries in orchard?

I need to add two meta tags. I have this:

MetaEntry FBphoto = new MetaEntry();
FBfoto.AddAttribute("property", "og:image");
FBfoto.AddAttribute("content", "image.jpg");
SetMeta(FBphoto);

MetaEntry FBdescription = new MetaEntry();
FBdescription.AddAttribute("property", "og:description");
FBdescription.AddAttribute("content", "Some description");
SetMeta(FBdescription);

Unfortunatelly SetMeta adds only second metaentry (FBdescription). How can I achieve to add them both?

The reason this doesn't work is because if you look in ResourceManager.SetMeta there's the following code

public void SetMeta(MetaEntry meta) {
if (meta == null) {
    return;
}

var index = meta.Name ?? meta.HttpEquiv ?? "charset";

_metas[index] = meta;

}

Therefore your second call to the method is overwriting the entry from the first (the one with the key "charset").

If you look at a module called Social Media Tags on the Orchard Gallery and the source on GitHub they are adding the tags in the driver building up the meta in a helper class

In that code, they are just using the key as the property name without the colon so your code would become

MetaEntry FBphoto = new MetaEntry();
FBphoto.Name = "ogimage";
FBphoto.AddAttribute("property", "og:image");
FBphoto.AddAttribute("content", "image.jpg");
SetMeta(FBphoto);

MetaEntry FBdescription = new MetaEntry();
FBdescription.Name = "ogdescription";
FBdescription.AddAttribute("property", "og:description");
FBdescription.AddAttribute("content", "Some description");
SetMeta(FBdescription);

which does get both the tags on the page. I don't think there's any harm in having the name attibutes, they just aren't required, but you'd need to confirm this.