Enzo recieved Bob protocols along with his field commission in the Web World Wars. He was Enzo, with Level 1 Guardian code added to his own. Normally he would have been trained by Bob and sent to the SC to complete his training, where he would likely have recieved his own Guardian identification protocol. His Programming as a Guardian was never completed, you will not he does not have the gung-ho "mend and defend" attitude of the other (uninfected) Guardians, rather he has the gung-ho "blow it up, yeah that will fix it" attitude. One would contribute this to the fact that He spent more time in GS mode rather than Guardian mode, the behavioral protocols gained in that mode dominate the Guardian behaviorl protocols. So, he still has the urge to protect, but he also has the urge to destroy.
Getting back to ID protocols, it is like haveing a chip under skin that sends out a signal on a specific frequency, Enzo's icon was set by Bob icon to have the ID and was calibrated to Bob signal, so they shared IDS, and like i said earlier that would have changed when Enzo was sent off to the Academy.
Glitch had nothing to do with Enzo's code, as Glitch was broken when Enzo got him, there was no exchange of code.
(off topic, I wonder if anybody has writen any fics about the trio of Guardians that were sent to get Bob in e3.2.4. They stuck me as sort of bounty hunter types, with jurisdiction over the know net... maybe like an IA (that is Internal Affairs) team of sorts. You know, that anser to the Question "Who polices the police?". PErhaps like Matrix there had been previous Renegade Guardians and it was their job to track them down and bring them to the SC for processing.)