Thierry Banel writes:
There is no way to ensure a single call to
(org-babel-gnuplot-process-vars) without modifying ob-core.el. I don't
want to do that because I would have to change a lot of babel backends.
But that is the right fix to apply, unless there is a reason for the
input vars to be processed multiple times. I haven't looked at the
Babel code in the last two years, but generally I'd suggest that each
argument should only be processed once per Babel block since the second
processing could have unwanted side-effects.