Miles Morales currently costs $49.99 whilst the Ultimate Edition which includes the Spider-Man remaster is $69.99, meaning that if you simply get the bundle, you’ll save $19.99. As per usual with this kind of bundle, getting the two in one fell swoop is the cheaper alternative.
If you’re out of the loop and haven’t tried Marvel’s Spider-Man Remastered, it features native 4k support, 60FPS, adaptive trigger support, haptic feedback, 3D AudioTech, faster loading screens, ray-tracing, a visual overhaul, and model updates with a complete re-do of Peter Parker to better match his voice actor. Buying the remaster also means that you get access to all of the DLC from the PS4 version and these are, naturally, remastered just as the original game is, as part of the bundle.
Sony has yet to make a statement on the issue regarding buying the remaster for those who own the PS4 version along with its season pass, but, if this is indeed an error, hopefully, an update or fix rolls out soon. If not? Perhaps free upgrades are in store, although this would seem unlikely since it was bundled in with Miles Morales already.
The PlayStation Store listing also seems to have the release date for Spider-Man: Remastered as August 28, 2019 whereas Miles Morales and, subsequently, the remaster, launched on November 12, 2020. The store page could definitely do with some fine-tuning, but at least the option for players to get the remaster alone is there.