There have been quite a few trainers, cheat programmes and editors for Dune II released by third parties back then, and some are still found today at cd.textfiles.com and other various places. The following files are of historical interest mostly, although most are still functional.
NOTE: Programme titles and descriptions below are taken from the original documentation, if possible.
D2CHT10.ZIP - DUNE 2 CHEAT The Ultimate Cheat Program v1.0 by Jens Defendorf. [a unit and structure editor for v1.0]
DUNE2CHT.ZIP - C.k.'s Dune ][ INI file editor.
DUNE2ED2.ZIP - Dune 2 Save Game Editor & Dune 2 Scenario Editor by C.k.
DUNEEDIT.ZIP - Dune II: Building Of A Scenario by Beloglazov V.
EDDUNE.ZIP - DUNE II Saved Game File Editor Version 1.5.
DUN2TR07.ZIP - Dune II : MEGA-Trainer by Network (for v1.07).
DUN2TR10.ZIP - Dune II : MEGA-Trainer by Network (for v1.0).
DUN2TRNR.ZIP - RAZOR DUNE ][ TRAINER.
DUNE2_T2.ZIP - DUNE II Trainer V1.1 by Hal 9000.
DUNE2_TR.ZIP - Dune II trainer.
DUNE2CHT.ZIP - Dune ][ cheat. [money trainer]
DUNE2MM2.ZIP - Dune 2 Money Maxxer v2.0.
DUNE2TRN.ZIP - DUNE ][ TRAINER. [money trainer]
TRDUNE2.ZIP - DUNE II Trainer V1.1 by Hal 9000. [same as above but doesn't have the extra patch file]
DUNE2AIL.ZIP - Dune II GUS patch.
DUNE2FAQ.ZIP - DUNE II FAQ & Strategy Guide Revision 1.3.
DUNE2PAT.ZIP - Westwood's Dune II v1.07 patch with READ.ME file included.
DUNE2SAV.ZIP - custom Dune II scenarios (in the form of saved games) by Bjorn.
DUNE2STP.ZIP - a version of SETUP.EXE that allows selection of different languages and separate sound devices for music, speech and sound effects. Seems like an official, if early, release but no readme has been supplied.