Cookies are shared between same base domain

I have installed kobo on two different instances, but I am using the same base domain name, changing the prefixes, for example:

kpi-first.site.com
kc-first.site.com
ee-first.site.com

kpi-second.site.com
kc-second.site.com
ee-second.site.com

Now I have noticed that cookies are being shared between the sites, if I log out of the first one, it also logs out of the second one. Then if I log on the first one and then on the second one, the forms loaded in the first one are no longer available, which tells me that the cookies were replaced. Does anyone have any idea how to solve this problem?

Try using sub-sub-domains. Eg. kpi.first.site.com