2 different UTM_source passing in a single link

Question

I've always wondered what happens when 2 different utm_source are passed on in a link

http://example.com/?utm_source=A&utm_source=B

In this case, which source will be passed on?

Answer 1

In this particular case no source will be passed on - since your link is missing the required medium and campaign parameter the source parameter will be ignored.

If you add medium and campaign the second source parameter would be used.

You can easily test this by generating a link to your site with double source parameters and then check the traffic source in the real time reports.