Args with multiple identical keywords

Hey,

is it possible to parse argument lists containing the same keyword
multiple times, having each occurence of the keyword values assigned to
another variable?

For example, would like to parse a configuration like this:

SomeElement(FIRSTKEYWORD 1, FIRSTKEYWORD 2, ..., SECONDKEYWORD a,
SECONDKEYWORD b, ...);

Currently only the last value of a keyword group is parsed and returned
as a result after consume() and all additional identical keyword
arguments are removed from the configuration string.

The only solution i see so far is having a single keyword and
concatenating all values into a single argument to this keyword. This
keyword is then parsed as a string, splitting the string and passing the
parts to additional argument parsers of the right type.

Does anybody know a better solution, which can directly be handled by
the argument parser?

Regards,
Sascha