The steemproposal's own website is unclear as to how such votes are added and it does look like that a proxy-giver could vote twice - once by themselves and once through their witness-proxy-holder.
Yes, that's really a bit confusing on there.
But it is extremely unfair that a proxy-giver's vote is annulled by the proxy-holder - that needs serious changing.
At least people need to know about this, so that they will reset their proxy, if they want to (effectively) vote for proposals. I will keep an eye on that and I think I will mention it in my next posts again.