double event handlers calls fix

res/scripts/stdlib.lua

@@ -135,6 +135,18 @@ function events.on(event, func)
     table.insert(events.handlers[event], func)
 end
 
+function events.remove_by_prefix(prefix)
+    for name, handlers in pairs(events.handlers) do
+        if name:sub(1, #prefix) == prefix then
+            events.handlers[name] = nil
+        end
+    end
+end
+
+function pack.unload(prefix)
+    events.remove_by_prefix(prefix)
+end
+
 function events.emit(event, ...)
     result = nil
     if events.handlers[event] then