what do you mean by:
"why there is only one cookie in file? "
if you mean that you went into your cookie folder on your computer and only found one file for your domain, this is fine, and normal.. but both values are stored in that one file, if you poke around in it you can find both values, and if you read it carefully enough you can see where the seperation of the 2 'cookies' are within the file..
if thats not what you meant, please explain 🙂
Also, have you tried to test the values of the cookies, to see if they are both being set?