It's not so difficult to produce two md5-collided exe files

[foosaa]

For another example and a detailed walk-through which you could try, see the following link:
http://www.win.tue.nl/hashclash/SoftIntCodeSign/

Authors
Marc Stevens, CWI, Amsterdam, The Netherlands
Arjen K. Lenstra, EPFL, Lausanne, Switzerland, and Bell Labs, Murray Hill, USA
Benne de Weger, TU/e, Eindhoven, The Netherlands

are the pioneers in producing MD5 collisions across a variety of things!

and if you want to deep dive into more specifics, then visit

http://www.win.tue.nl/hashclash/ChosenPrefixCollisions/

Hope it helps someone!