There are two different alarm ID's in Spectrum.
There is an integer alarm ID assigned to each alarm generated by the SpectroSERVER. Basically, when you start the SpectroSERVER, the first alarm is assigned alarm ID 1, the next 2 etc. The same SpectroSERVER will reuse alarm ID's. This integer alarm ID is not guaranteed to be unique across SpectroSERVERs in a Distributed SpectroSERVER (DSS) environment.
The Global Alarm ID is unique to each SpectroSERVER. No two SpectroSERVERs in the same DSS environment will assign the same Global Alarm ID to an alarm.
The Spectrum documentation defines them as follows:
Alarm ID - Specifies the numeric identifier that CA Spectrum assigned to the alarm.
Global Alarm ID - Specifies a unique numeric identifier that CA Spectrum assigns to the alarm. Unlike the Alarm ID, the Global Alarm ID is not only unique within the CA Spectrum environment, but also can be passed as a unique identifier to other environments. Use this value to pass a unique identifier to third-party software.