I doubt they would use different diodes. In the hardware world its usually cheaper to underclock, undervolt, underutilize a part than it is to make two versions. They may bin them and put the best ones in the more expensive models (means cheap ones can be good, expensive ones are more likely good) but I doubt they would make two different diodes.
Same reason most cpu cores within a model range are identical, and video cards within a range are often identical but with cut down features. With video cards this trend sometimes starts to change though since they cost so much to manufacture at some point it does become cost effective to produce one with less transistors and a less complex circuit board, but with something as cheap as a laser diode, I doubt it would be cost effective to produce two unique parts when designing and tooling up for mass production of one will do. Especially when first released (Example: when AMD started releasing dual cores and tri-cores based on its new architecture they were just quads that had weak cores disabled or perfectly fine quads. I believe later dual cores got their own die while tri-cores are still really quads).
