look at this q/a
http://stackoverflow.com/questions/25088899/selenium-webdriver-throws-exception-when-trying-to-run-via-ant
I have checked this already.
I dont see any duplicate jars in my project.
I have deleted the complete .m2 directory and tried to download the jars again.
Same issue
for me, your project is running fine, please check your jar files or use some other system.