IIRC, the first 1999 DVD is based on a master used for one of the last widescreen LD editions. It's English 5.1 is a DD 448kbs of the LD tracks reportedly of the 70mm mix without any adjustments (more on this later). Sony later did a ground up 5.1 remix using the 4 channel M/D/E stems and soundtrack recordings which was used on the Japan exclusive Superbit DVD as well as on the 2005 R1/2 DVDs (it's also the basis for the recent foreign dub 5.1 tracks). When Sony did a new master for the 2009 BD, they went back and remastered the 70mm mix for the English 5.1 track (which is used on all recent releases). It added the aggressive LFE from the Superbit remix and has some volume adjustments with certain SFX/sounds along with stereotized mono rears, but other than that it's similar to the 5.1 on the 1999 DVD.
The 2.0 mix on the other hand, is interesting. The early LDs have the 2.0 track from a Dolby Stereo optical element, while later SE letterbox releases have the 2.0 sourced from the studio master tape. There's been reports of extremely rare DVDs of Ghostbusters with a version of the 1999 disc having a pan and scan version on one side (like GBII) and a single disc fullscreen edition from 2004. The single disc fullscreen has the same 5.1 options as the later widescreen DVD, while the 1999 flipper has a 2.0 track on the fullscreen side in addition to the 5.1 (probably using the 1999 VHS master since that had a 2.0 from what sounded like the studio master tape).
The 2.0 on the 2019 35th Anniversary BD as well as the Ultimate Collection UHD is believed to be sourced from the Dolby Stereo optical track rather than the studio master track.