2 networks on 1 WP instalation

Is this possible:
I want to create 2 networks (with 2 different domains) on one WP instalation.
Example:
mysite1.com with sections like this: mysite1.com/sec1, mysite1.com/sec2 etc; and:
mysite2.com with sections like this: mysite2.com/sec1, mysite2.com/sec etc.