Dinosaurs from Benin 1984, these two FDC are not official one but in USA produced


Note: Thanks to Bear for these nice covers
I'm a bit confused by the following signature on the back side of these covers:
"@1986 Fleetwood, Cheyenne, Wyoming, U.S.A. 1170758
Original an by Gene Jarvis"
How come that covers with post mark of "First day issue" of 1984 produced in 1986 ?
According to
http://www.artworkoriginals.com/EB5TB55E.HTM " This painting was originally published on the Fleetwood® First Day Cover for the Republic of Benin 75F Anatosaurus stamp issued December 14, 1984.
Artwork Copyright © 1986 Unicover Corporation. All Rights Reserved under United States and international copyright laws."
Can it be that Copyright protection line was printed on the backside of the covers 2 years later on still not sold covers ?