jQuery UI "Bounce" effect toggles twice

jQuery UI "Bounce" effect toggles twice

Hi!

I have 4 pictures "Goog", they are hidden. I want to fadeIn two of them, and then launch "Bounce", like second effect. But I can do it only with button, not in fadeIn complete function:

jsfiddle:   link

I suggest my problem is with "bounce", it toggles twice on load..  api.jqueryui.com/bounce-effect

Best regards,  
Gennady