Sunder more than one Immunity

I just noticed that the renewed sunder charms seem to be like annis and torches. You can only have one in your inventory (or personal stash). I only noticed because I wanted to renew a latent one and my char refused to do it because I already had a renewed one with me. They did not have the same element, though.

Was it like that right from the start? Does the same restriction exist on latent sunder charms? I wasn't able to test because I had only one latent charm.

Not saying that it makes any sense, but if I wanted to have more than one element immunity broken by charms, I would have to use the latent version or use the old sunder charms, is that correct? I don't have any build in mind where I would need this, but I feel unnecessarily restricted. I mean, I do get that you are not supposed to stack charms for the same element (though you should also suffer from the stacked negative resistance), but if I wanted to have a -70% penalty on all of my resistances, why not let me do that?

Original sunder chams aren't unique, they only sunder one immunity at the price of lowering your own resistance.

Renewed sunder charms are indeed unique-equipped. Probably because of the lowering enemy resistance part that they don't want you to stack.

The only way for you to sunder 2 immunities is by holding a renew and a latent (or original) sunder charm.