Jumbugz Questions

Ok i made 2 jump bugs.. here are the demos (one is jumping and the other one is doble ducking)

http://users.cjb.net/dogos90/bugz.rar

my questions are..
there are 3 demos. In two of them (jumpb.dem and jumpb2.dem) i made the jumpbug but in the other one (jb.dem) i am not sure.. because i dont get hurt but it make a sound like if i was jumping from a lower block not like the jumpbug :S
then.. in the first jumpbug i made it jumping but in the other one i made it dobleducking.. the thing is that the doble ducking one was much easier.. in fact i did it first try.. is there any difference or was just luck ? :confused:
Ok thats all :rolleyes:
ah btw, all the demos where made on a public server so they cannot be checked but the settings are right.