There were definitely 2 different Colorado Belles. I know some of the background, though not all.
See the Herz book (pg. 108) where Belle #1 listed as 1980-1984 and Belle#2 listed as 1987 & on (the current one).

I have a 1987 Circus Circus, Inc. Annual Report which notes the following dates for their Laughlin properties:
Feb 1983 - C C acquired The Edgewater H & C in Laughlin.
June 1984 - added 453 rooms to Edgewater
Dec 1986 - opened 615 room hotel phase of Colorado Belle (while casino being finished)
July 1987 - scheduled completion of casino and remaining hotel rooms at the Colorado Belle.

I'm not sure if the original Belle was located on current Edgewater property, or was on land where the current Belle is located. But it was in that vicinity. I don't have first hand knowledge of the original Belle. The Circus Circus expansion into Laughlin in mentioned in the book "High Stakes" by Gary Provost (published 1994) but no mention of the original Belle in it.

I'll scan a photo from the 1987 Annual Report cover & attach it to this post, just FYI.