These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Before Brooks & Dunn was founded, both men were solo singers. Kix barely charted with a song called "Sacred Ground," which would later be a #2 hit for McBride & the Ride (it got blocked from #1 by "Achy Breaky Heart"). Incidentally, McBride & the Ride's lead singer and bassist, Terry McBride, would later co-write several of Brooks & Dunn's songs and play bass in their road band.
"Boot Scootin' Boogie", although written by Ronnie Dunn, was first recorded by Asleep at the Wheel.
Their version of "My Maria" is far better known than the B.W. Stevenson original.
Same with their version of "Husbands and Wives" vs. Roger Miller's original.
...and, at least stateside, their 2001 version of "The Long Goodbye" vs. Paul Brady's original or Ronan Keating's subsequent cover (Brady and Keating wrote the song).
"Every River" was previously recorded by Kim Richey. Zig-zagged in that Kim sang backing vocals on Brooks & Dunn's version.
"Building Bridges" had been released by its co-writer, Larry Willoughby (Rodney Crowell's cousin), and later by Nicolette Larson. Neither version cracked the 40, while Brooks & Dunn's was a Top 5 hit.
Dork Age: Tight Rope, their first album not to go platinum. It was poorly received for its tired production (this was the only time they ever worked with Byron Gallimore) and poor song choices (including a tepid cover of John Waite's "Missing You"). It seems even B & D themselves didn't like it, as "You'll Always Be Loved By Me" doesn't appear on their second Greatest Hits Album even though it was a Top 5 hit.
Older Than They Think: "Only in America" tends to get lumped in with the wave of patriotic country songs released after 9/11. However, it was released in June 2001.