I don’t speak German but if you go to the bottom of the Tafel catalog they have a pic of an adjustable one.
http://www.tafel-tuning.de/download/kataloge/TT-F.pdf

That one does not support both tubes, like the one in the first picture

So Tafel-tuning and MBT engineering both have a beam-brace that`s adjustable, but only supports the lower tube.

Is supporting both tubes needed? I have seen some pictures of original VW parts that supports both tubes, perhaps a link-pin model. Did they some time change to a single-support version?

You know what? I think if enough people were interested, Lanner at VDub Engineering could probably cook up the 2 tube version.

Vdub Engineering

Jason