I'd love to enter a quilt that I made because I am curious as to how a judge would judge it. I am a person who does the entire quilt from the piecing to the hand quilting and completing it w/ the binding. I don't have a problem w/ people using other's patterns - the piecing and choice of fabrics will make the final product look different.
I also don't think I have a problem w/ entering the quilt in multiple shows. Heck, if I had something that good, I'd want to show it off for all to see!!
I will say that I think there is a huge difference in competing w/ pros and those of us who quilt as a hobby.