I have to admit, I would be irritated too. I KNOW I should be flattered but I am going thru the exact same thing. My sister in law is allowing her daughter to copy my daughters birthday party (they are only 6 days apart in age). It is such a dumb, immature thing to be upset about. There are starving children in Etheopia for goodness sakes! But this is my world and my drama and just give me room to be upset (oh husband of mine!!)! UGH!
I can relate girl....temper tantrum on! In all, nothing much you can do about it but have your own little pity party (in your mind and to your best gal pals) and vent to yourself that your friend needs to get her own darn imagination and find her own resources! OK, off my soap box.
Kudos to you for throwing a fabulous event KWtennis4. So fabulous that your friend would want to copy it. Happens to me a lot. I use to be an event planner and even now, when I plan the most mundane birthday party for my 7 year old (glow n the dark bowling with a Tinker Bell theme) my lazy sister in law COPIES ME! ARGH!!! hahaa! 