Q:

Google Analytics - async tracking with two accounts

I'm currently testing GAs new async code snippet using two different tracking codes on the same page;
_gaq.push(
    ['_setAccount', 'UA-XXXXXXXX-1'],
    ['_trackPageview'],
    ['b._setAccount', 'UA-XXXXXXXX-2'],
    ['b._trackPageview'] 
);

Although both codes work, I've noticed that they present inconsistent results. Now, we aren't talking huge differences here, only 1 or 2 visits / day every now and then. However, this site is tiny and 1 or 2 visits equates to a 15% difference in figures. Now, the final site has much more traffic, but my concerns are; 

will this inconsistancy scale with traffic? 
assuming not, is a slight variation in recorded stats an accepted norm?

A:

You can avoid the conflicting cookies by setting a different domain for google analytics.
<script type="text/javascript">
//<![CDATA[
var _gaq = _gaq || [];
_gaq.push(['_setAccount', 'UA-NNNN-1']);

// primary profile
_gaq.push(['_setDomainName', 'www.domain.com']);
_gaq.push(['_trackPageview']);
_gaq.push(function() {
    // create the second async tracker
    _gaq._createAsyncTracker('UA-NNNN-2', 'blogTracker');
});

// secondary profile (this is the default domain setup if not specified) 
_gaq.push(['blogTracker._setDomainName', 'domain.com']);
_gaq.push(['blogTracker._trackPageview']);  
//]]>
</script>

This will keep the cookies separate.
Note: I am using this setup to track events in a second profile to keep my bounce rate numbers accurate. The second profile tracking code is only used on my blog, thus, is not a complete profile on purpose.  

