I loved that game.
Played it on my Amiga 500 a LOT !! Till past 11th space station i think, got blocked there from another code bug (there is a first code bug i found a code for in a magazine arround mission 13 or so)
Later played it on my A1200 and i remember having the same problems than you with the keys working 2 or several times per click.
I found some boot disk to make my A1200 work as an A500, and it worked well with it. Don't remember it's name tough.
Some of us from this forum started a project about a year or 2 (already !? damm!) agoo to make a captive remake. Unfortunatly most of us more or less abandonned the project, and we're only like 2 left. We have a working demo i made, but unfortunatly i'm playing Asheron's call 2 again (some old MMORPG that sucks all my time up atm