Why can't you create multiple TXT records with the same name?

[micheljung]

If I do this:

resource "hcloud_zone_rrset" "txt_onmicrosoft_com" {
  zone = hcloud_zone.main.id
  name = "@"
  type = "TXT"
  records = [
    { value = "\"NETORGFT14001567.onmicrosoft.com\"" },
  ]
}

resource "hcloud_zone_rrset" "txt_spf" {
  zone = hcloud_zone.main.id
  name = "@"
  type = "TXT"
  records = [
    { value = "\"v=spf1 include:secureserver.net -all\"" },
  ]
}

I get:

RRSet already exists
 
Error code: uniqueness_error
Status code: 409

For all I can tell, this is because I try to create two TXT records with name @.

Interestingly, this does not seem to be a problem via the UI:

When I do it like so:

resource "hcloud_zone_rrset" "txt" {
  zone = hcloud_zone.main.id
  name = "@"
  type = "TXT"
  records = [
    { value = "\"v=spf1 include:secureserver.net -all\" \"NETORGFT14001567.onmicrosoft.com\""  },
  ]
}

It works, and AFAIK it's the same as having two TXT records:

But it still begs the question: Why does it work via UI but not via Terraform? I can imagine cases where you'd want to have hcloud_zone_rrset/txt/@ spread across multiple files (think modules that create their own records), so this would be handy to able to.