I hope I have now resolved my problem with ghosting appearing on lunar images with my 450D. I finally had a night with a clear period long enough to take subs of the Moon at multiple exposure times. First I tried 1/1000th @ ISO800 which is what I have used up to now, then 1/500th @ ISO400 and finally 1/200th @ ISO200.
Whereas I was hitting problems with ghosting on the 1/500th and slower frames before this time I configured APT to use a two second delay after locking up the mirror before opening the shutter. This completely eliminated the problem and I managed three clean images at all three exposure lengths.
To confirm I also shot a few frames of 1/200th without the mirror lockup delay and approximately half the frames showed a ghosted image.
I’m happy with this now and have started shooting all the subs for lunar images using exposures of 1/200th @ ISO200. I think the results have definitely improved compared with those I took previously using the 1/1000th shutter speed.