> ...this is exactely what I don't need: The imported templates 
> have to override the importing as they are more specialized 
> as the ones. Shall I just turn arround the mechanism and 
> import the general stylesheet into the more specialized?

Yes, absolutely. You should always import a general-purpose module from a
special-purpose module, never the other way around.
> 
> Besides this, for curiosity:
> You state that "[i]t may well cause errors due to the 
> presence of duplicate declarations; in fact, if the 
> stylesheets contains definitions of global variables or named 
> templates, and is included more than once at the same 
> precedence, such errors are almost inevitable." (XSLT 2.0, 
> 3rd ed., p. 330)
> 
> - What does "may" mean? 

This is in relation to including the same module more than once.

I think the "may" is correct: There are cases where this won't throw an
error, for example, if the modules are empty, or if they contain template
rules (match templates) that are never matched. But I wouldn't defend the
"almost".

Michael Kay
http://www.saxonica.com/