I've seen this been done before, and IME it's reasonable behavior.
I've seen so many instances of computers configured with DNS servers which are extremely slow, or provide garbage results, that adding a known good DNS server to the list, and then parallel resolving across all of them is a perfectly legitimate thing to do.
I've seen so many instances of computers configured with DNS servers which are extremely slow, or provide garbage results, that adding a known good DNS server to the list, and then parallel resolving across all of them is a perfectly legitimate thing to do.