Some Fence and Stair Rail swatches don't match when placed

Please investigate why some Fences and Stair Rails don't match.  Many of the Stair Rails from different packs are much darker than their coordinating fences when placed.  The screenshot below shows a small sampling of fences and their coordinating stair rail swatches.  The mismatch occurs with and without mods installed.  Tests with various lighting, above and below, did not make much of a difference.

Lower left: Perfectly matched Base Game Horizontal Aluminum Railing System and Ladder Style Horizontal Fencing
Upper left: Mismatched Castle Estate Heirloom Banister and Heirloom Handrail
Upper right: Mismatched Vampires Iron Stairway and Iron Railing
Lower right: Mismatched Cats & Dogs Hands Free Railing and Coastal Guardian Fence

Thank you for your time and consideration!