WardrobeGUI error

06:56:51 [ERROR] Could not load 'plugins/WardrobeGUI+.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.ClassFormatError: Duplicate method name&signature in class file ro/Velcea123/WardrobeGUI/Main
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:135) ~[spigot-1.8.8-R0.1-SNAPSHOT-latest.jar:git-Spigot-fdc1440-53fac9f]
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:329) ~[spigot-1.8.8-R0.1-SNAPSHOT-latest.jar:git-Spigot-fdc1440-53fac9f]
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:251) [spigot-1.8.8-R0.1-SNAPSHOT-latest.jar:git-Spigot-fdc1440-53fac9f]
        at org.bukkit.craftbukkit.v1_8_R3.CraftServer.loadPlugins(CraftServer.java:292) [spigot-1.8.8-R0.1-SNAPSHOT-latest.jar:git-Spigot-fdc1440-53fac9f]
        at net.minecraft.server.v1_8_R3.DedicatedServer.init(DedicatedServer.java:198) [spigot-1.8.8-R0.1-SNAPSHOT-latest.jar:git-Spigot-fdc1440-53fac9f]
        at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:524) [spigot-1.8.8-R0.1-SNAPSHOT-latest.jar:git-Spigot-fdc1440-53fac9f]
        at java.lang.Thread.run(Thread.java:745) [?:1.8.0_60]
Caused by: java.lang.ClassFormatError: Duplicate method name&signature in class file ro/Velcea123/WardrobeGUI/Main
        at java.lang.ClassLoader.defineClass1(Native Method) ~[?:1.8.0_60]
        at java.lang.ClassLoader.defineClass(ClassLoader.java:760) ~[?:1.8.0_60]
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) ~[?:1.8.0_60]
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:467) ~[?:1.8.0_60]
        at java.net.URLClassLoader.access$100(URLClassLoader.java:73) ~[?:1.8.0_60]
        at java.net.URLClassLoader$1.run(URLClassLoader.java:368) ~[?:1.8.0_60]
        at java.net.URLClassLoader$1.run(URLClassLoader.java:362) ~[?:1.8.0_60]
        at java.security.AccessController.doPrivileged(Native Method) ~[?:1.8.0_60]
        at java.net.URLClassLoader.findClass(URLClassLoader.java:361) ~[?:1.8.0_60]
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:101) ~[spigot-1.8.8-R0.1-SNAPSHOT-latest.jar:git-Spigot-fdc1440-53fac9f]
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:86) ~[spigot-1.8.8-R0.1-SNAPSHOT-latest.jar:git-Spigot-fdc1440-53fac9f]
        at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_60]
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_60]
        at java.lang.Class.forName0(Native Method) ~[?:1.8.0_60]
        at java.lang.Class.forName(Class.java:348) ~[?:1.8.0_60]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:64) ~[spigot-1.8.8-R0.1-SNAPSHOT-latest.jar:git-Spigot-fdc1440-53fac9f]
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:131) ~[spigot-1.8.8-R0.1-SNAPSHOT-latest.jar:git-Spigot-fdc1440-53fac9f]
        ... 6 more