I had been a Colt AR owner for 49 years now and had 12 new rifles and carbines, currently have four.
Never received that kind of tag, probably the factory forgot to remove it before shipping.
I received a factory tag on one of my non Colt AR carbine which was a LMT (Lewis Machine & Tool) model Defender 2000 lower half way back in 2005, thinking it was also a mistake.
That same year 2005 I bought a new LMT M4 carbine 16" barrel complete upper half and had no tag.