Two cookies with different domains

After migrating to F5, when user session time-out expired users get 3(or 4) different cookies.

Application logic is to have one domain cookie but now we have two ".Asp.Net.Cookie" with different domains, one of the cookies is with current sub-domains(aaa.bbb.ccc) and the correct one is main domain (bbb.ccc).

How I can remove this kind of problems with extra cookies and set just one cookie per server node?