I've always assumed that the different inserts would match them to a table as (to me) it makes much more sense but maybe they were.
Maybe it's because I've worked on the tables so I just think like that but it's logical to me because of that fact.
Payouts and chipping them up would be a bit of a nightmare though if all the same colour but with different inserts on the same table.
Likewise the first series with letters, they all denote a different table.
When they used generic chips they would use the same pattern on the same table not the same colour chips (as you know) so I suppose that's where I get my thoughts too.
As I say, maybe but doesn't sound practical to me.