How reliable is the Build Forge semaphore mechanism?

Could you tell me how frequently Build Forge gives the same semaphore to 2 jobs at the same time?

We recently observed the following

We are running buildforge 7.1.1.3-0-0028; RH Linux AS4; Oracle 10g

We have a Project with a step that acquires a semaphore to ensure no two Jobs simultaneously perform the selected activities

While testing this we launched 3 Jobs.
Build 1 - launched first
Build 2 - launched second
Build 3 - launched third

Build 1 acquired the semaphore.
Build 2 got to the semget step and started waiting for the semaphore
Build 3 got to semget step and also started waiting for the semaphore
Build 1 then failed

Expected behavior:
Build 2 is in front of the line and get's the semaphore

Actual behavior
Build 2 and Build 3 both got the semaphore.

From "Build 2"
237 02/26 03:28PM EXEC Semaphore (fakeStreamOne) obtained 13877 seconds after initial request.

From "Build 3"
237 02/26 03:28PM EXEC Semaphore (fakeStreamOne) obtained 12983 seconds after initial request.