I read this phrase here: "Zaydi [Shi`ite] twelvers". Of course, they are not Shi`ite twelvers by definition. My anonymous adviser on Shi`ite theology added this: "if
they count Zayd as an Imam, the Imams will no longer add up to twelve. If they
do not count him, they cannot be called Zaydis.
Now
there is one thing that is a bit too scholarly for media usage, but it is worth
noting, at least to attend to your thirst for Islamic history. There has been a
group within Zaydi Shīʿism, which came to dominate other Zaydi groups at the
end of the 2nd/8th century, whose views are quite similar
to Imāmī (later known as Twelver) views. These shared views concern the nature
of the Imam’s knowledge, his method of designation, the position on Muhammad’s
companions and other legal details. But they cannot, in any way, be considered
Twelver Zaydis."