Hi Kapishhohole.
To create more than 1 SPAN session on your cat6k with CATOS you have to use "create" keyword.
Something like this
set span tx create
Remember few guidelines
If you do not specify the keyword create with the set span command and you have only one session, the session will be overwritten. If a matching destination port exists, the particular session will be overwritten (with or without specifying create). If you specify the keyword create and there is no matching destination port, the session will be created
I am posting you the link for cat6k span configuration on catos please read the span session limits and config guideliens
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/sft_6_1/configgd/span.htm#1019851
HTH
Ankur
