/etc/texmf/dvipsj/config.duplong is in dvipsk-ja 5.98+p1.7b-1.1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | % config.duplong
% Configuration file for dvips. Load with: dvips -P duplong.
%
% Prints in duplex mode with binding on the long edge.
% Ignored on a simplex printer.
% Works on HP LaserJet IIISi.
%
% This file is built so it can be used both as the header file for
% PostScript and as the configuration file for dvips.
% (Note that dvips ignores any lines beginning with a space or a "%".)
%
% Volker Kuhlmann, 20 Feb 1995
% VOLKER@ELEC.CANTERBURY.AC.NZ
%
statusdict begin true setduplexmode false settumble end
%
{ % start a procedure so PostScript `ignores' the dvips options.
h config.duplong
} pop % PostScript cleanup
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