TeamCity can run multiple agents on one machine, but each needs isolated configuration and build resources. Install each agent in a separate directory; set distinct `name`, `ownPort`, `workDir`, and `tempDir` values in its `conf/buildAgent.properties`. JetBrains also recommends separate OS users to avoid conflicts in user-level caches.

Check that build configurations do not share mutable checkout paths or other resources. CPU, memory, and disk contention can reduce throughput, so verify actual resource use before increasing parallel agents. On macOS or Windows, follow the platform-specific service/startup instructions in the TeamCity guide.