This is the expected behavior in the same browser session, by default. If you want to have both the environment accessible at a time in your machine you may need to use multiple different browsers such as Chrome/IE/Firefox... or even you can access it in incognito mode.
The reason is SMSESSION is the cookie name which is getting generated by webagent on successful authentication which is same for all the Tiers(DEV/INT/QA/PROD).
If you really want to change the SMSESSIOn cookie name, you may need to go with Security Zone setup approach as below:
Refer this link - Security Zones for Single Sign-on - CA Single Sign-On - 12.52 SP1 - CA Technologies Documentation
Set up Security Zones
You configure SSO security zones using two Agent Configuration Object (ACO) parameters:
- SSOZoneName—Identifies an Agent's local zone by assigning it a name. The default name is "SM."
- SSOTrustedZone—Lists zone names that an agent trusts.
A single Web Agent instance supports only one local SSO zone, which you identify using the SSOZoneName parameter. An Agent implicitly trusts its local zone. Multiple zones cannot be named using the same Agent instance.
Based on the zone a web agent is configured to use, the agent generates the session and identity cookies with unique names. These names reflect the zone affiliation. For example, for the default zone named "SM", the session cookie is named SMSESSION. However, if an agent is configured to use a zone that is named "MY" instead of "SM" the SMSESSION cookie becomes MYSESSION.
Agents enforce zones by storing the zone name in the session and identity cookies. Users cannot rename the session or identity cookies to change their zone. When the agent validates these cookies, the agent verifies whether the zone name stored in the cookie matches the prefix in the cookie name.