Not necessarily. This was introduced around TS2009 or TS2010.
The KUID:2 format was developed to better handle asset-versions.
Prior to this, assets were updated by entering in a new KUID into an obsolete-table in the config.txt file.
This had issues because assets could be superseded by people who wanted to mess with others, and there were a number of them in the past, and also this method was prone to typos. Typos that caused assets to totally change to something else such as a Textile Mill becoming a canal lock when the KUID was unintentionally typo'ed with a 68 instead of an 86.
With the new KUID:2 system, that was resolved and allowed 126 possible versions per asset using the same KUID with the only thing changing is the version number or suffix found after the right-most colon.
I think the KUID2 system arrived with TRS2004.
Here is the bit of the expanded manual for TRS2004:
14.1 KUID System
Whilst you should not need to know much about the KUID (or Koolthingz
Unique IDentifier) system, it is a term you will come across if you start
delving into the world of custom content. A KUID is simply a way of
identifying content for your TRS2004 software. Here is an example:
<KUID:43750:12345:02>
The first part of the KUID (43750 in this example) identifies the content
creator, so all content from any particular author will have the same first
set of digits. When you register at Planet Auran, you will be given a unique
content creator I.D. that you can find in your User Profile.
The second set of digits is the unique identifier for a specific asset from
the author.
New in this edition, there is also a third number. This is the item’s version
number and is used to allow Content Creators to update their creations
without having to introduce a new KUID.
My copy of TRS2004 has plenty of KUID2 items installed.