i runned more test. 
level1
the first time i play the layout, everything is fine.  
i die , retry . the bug is here.    i die, retry . its gone. (and dont seem to come back)
level1
first time ok > goto lvl2 > ok 
i die : go back lvl1 > bug is here, die, retry, bug is gone (and dont seem to come back)
level 1 ok > level2 ok >level 3 ok    
i die: checkpoint lvl3 > goto lvl3 >bug is here.    die, retry , bug is gone (and dont seem to come back)
i'd really appreciate some help on this..    
maybe i should done something with UID to avoid that ? but i dont know really how to use it.
or maybe use a different organisation in my events ?