I work for a world wide digital agency and I build a lot of websites or campaigns for my clients. I always create a new Google Analytics account for every website/campaign which is used internally by my company to generate traffic (visitors, pageview, etc) and goals report.
As you may know, setting up a Google Analytics tracking code on your website is pretty easy as you just need to copy & paste the code from Google and place it somewhere (above </body> tag) of your website. However, if client also want to track their site by themselves, the process is a little bit complex because you have to track in parallels. It means you need to setup multiple Google Analytics tracking codes on your website.
Below is a piece of code I usually use to track 2 GA tracking codes in my web pages:
And a function use to track events or custom function calling within Flash or Ajax:
Note: please update UA-XXXXXX-Y and UA-XXXXXXXX-YY with your real Google Analytics tracking code.