I already own Doom 1 and 2, but I'm curious. if you buy Doom 1 + 2 now, do you still get the previous Enhanced versions separately? or are those just obsolete now?

PCGamingWiki says they're still bundled in, but I don't know for sure.

Old DOOM 1 & 2 should be bundled with the new release.
If you already owned DOOM 1 or DOOM 2, it should have been added to your library for free.

I currently have DOOM 1, DOOM 2, the enhanced versions and the new remaster in my gog library.

After looking on gogdb, I'd say probably yes.

https://www.gogdb.org/product/1317223010#references

includes the DOOM II and DOOM (1993) bundles which each are the DOS game (+ Final Doom in cas e of Doom 2) and the Unity game.