different cache per user agent

[Marko Kruijer]

I've got Varnish working after some struggling, for testing purposes 
I've set the objects ttl to 15 secs.

I noticed that when calling a page from Firefox, and immediately after 
that from Internet Explorer, the served page is different. They are 
however cached for 15 secs.

Is this default for Varnish? If I'm correct it is not, there are NO 
cookies set. What can cause this behaviour?

Regards,
Marko