When you install a 11.x Agent, the Windows Service's Service/Display Names associated to that agent goes with the Agent Name selected during the installation.
This Windows Service Name is not being changed as part of r12 upgrade.
So, if there was an Agent Name called "r11.5 Agent' selected during the install, then that Agent Name (as well as Service Name/Display Name on the Windows Service) would persist for the Windows Service for the Agent in r12.
It will not be touched by the upgrade process.
Release : 12
Component : CA Workload Automation System Agent
This is expected behavior from the agent upgrade on Windows. The Display Name of the Windows Service should not be depended upon for Agent release info.
To obtain correct Agent release info, CybAgent -vv is a better approach