During the initial days of CRM, this is how Zoho implemented. Technically, Zoho did generate 2 running id's during run time, one will be the Record id and the other as Case id. Zoho purposefully made a difference as 1 or 2 (2 in your case) to make sure that Zoho didn't expose the Record ID upfront. Zoho had a plan to completely shorten the case id to more 4 digits but that didn't happen.
If this is causing an issue a case can be raised.