I registered another spelling for my domain name. I point them at the same IP with DNS set-up tool.
How do I tell which one my visitors come from more? Would I be able to view that kind of statistics in Google Analytics?
You can set up Google Analytics for multiple domains. When you create the tracking code it gives you that option and displays the relevant code to do that. It also tells you how to track clicks between domains so that they don't get counted as new visitors, but as people are either on one domain or the other, that doesn't matter.
Once that's up and running you can then look at the stats to see which domain people arrived at when they first came to your site.
If both domain are displaying the same content, you should redirect one to the other using 301, otherwise google (panda) won't like it very much and you will loose ranking.
In this case redirection will appear in google analytic.