I don't think event serialization is what you want... The value you pass on a serialized event is a lifetime value... as in if I pass "event1:a" then no other instance of "event1:a" will ever track again.
Event serialization is used for things that should only be counted once ever... like purchase transactions (passing a unique order id, so that if something happens and that same order id is passed to Adobe, it can be ignored as a new purchase), or something like a user registration (where the user's unique system id is passed, once a user id is registered, no future sends of this id will be counted as a registration). This can be helpful to pass on something like a login event, if your developers can't tell you when someone is new, you can use this unique ability to try and find the difference between a login and a "first time" login (i.e. user is registered).
It should also be noted that event serialization will only take a maximum of 20 characters (something I actually put in an idea to raise the characters it would accept, since a lot of development now is using 36 character guids... so serialization on a partial of the unique value isn't a great option).
However, in your scenario, I cannot see how or why you would need to record a unique event based on serialization....
Maybe you can provide a little more info as to what this list is doing and what you are trying to report on?