Hi Just to document this discussion a bit more:

Ihor writes:
>Horst Leps <horstleps@outlook.de> writes:
>
>> #+latex_class: koma-article
>
>This is non-standard.
>What is your value of org-latex-classes?

There is a translation from koma-article to scrartcl in the
org-latex-classes, so that is not the problem.

>> Makes:
>> ...
>> \usepackage[germanb]{babel}
>> ...
>> \usepackage[greek,german]{babel}
>> ...
>> -------------------
>>
>> ! LaTeX Error: Option clash for package babel.
>> -------------------
>>
>> Only one latex run. Tableofconts Table remains empty.
>>
>> Supposition:
>>
>> 1. The Latex source contains {babel} twice, but only once is allowed.
>
>ox-latex tries hard to not duplicate babel. I am unable to reproduce
>duplication with your file (but with #+latex_class: koma-article removed)

Despite this, there is a repetition, and the clash is because ox-latex
wants ngerman wiith
#+language: de
while Horst wants to use germanb. The clash is between what ox-latex
generates and what Horst tries to add with #+LATEX_HEADER:

Actually, he also needs greek and for that I have recommended to customise
variables so that fontenc is "LGR,T1" and the parameters for babel are
"greek,AUTO", instead of trying to add a #+LATEX_HEADER:
\usepackage[LGR,T1]fontenc, because that also generates a package
option clash.

That is something we might need to explore more, if/when people need/want
to use pdflatex instead of luatex or xelatex.

>> 2. There is an error in my Orgmode code because it exports {babel} once
>> too many
>
>Does the problem persist without #+latex_class: koma-article?
Once again, yes, because it is mainly a matter of #+language.
I think we need the following
1) more docs on #+language
2) more thought on multilingual documents (#+language: gr,de)
3) more though on documents with multiple font encodings.

Best, /PA
-- 
Fragen sind nicht da, um beantwortet zu werden,
Fragen sind da um gestellt zu werden
Georg Kreisler

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