Lots of 'em are multi-platform.
Aa! Megami-sama! is an updated version of the PC-98 original.
Angelique Special and Angelique Special 2 are also on PC, Saturn, and PS1.
Angelique Tenkuu no Requiem is also on PS1.
Blue Breaker is also on Saturn and PS1.
Blue Chicago Blues is also on 3DO, LA, PC, Saturn, and PS1.
Classmates 2 is also on SF, PC, Saturn, and PS1.
Der Langrisser FX is a remake of a Langrisser II on MD and SF; it's also on PC, Saturn, and PS1.
Dragon Knight 4 is also on SF, FM Towns, PC-98, X68000, PC, Saturn, and PS1.
Farland Story FX is an updated remake of the PC-98 original; it's also on SF, Saturn, and PS1.
Fire Woman Matoi-Gumi is also on PS1.
First Kiss Story is also on PS1 and PS2.
Fushigi no Kuni no Angelique is also on Saturn, PS1, and GBA.
There's Galaxy Fraulein Yuna 3 on both Saturn and PS1, but I'm not sure if they're the same game as Galaxy Fraulein Yuna FX.
There's three SF Zenki games and one for GG, but I don't know if any of 'em are direct ports of Kishin Doji Zenki: Vajura Fight.
Lunatic Dawn is also on FM Towns and PC-98.
Mahjong Gokuu Tenjiku is also on SF, 3DO, Saturn, and PS1.
There's Power Dolls and Power Dolls 2 on PC-98 and FM Towns, but I don't know how they relate to Power Dolls FX.
Return to Zork is also on PC, FM Towns, Saturn, and PS1.
Super Real Majhong PV is also on PCE, SF, 3DO, and Saturn.
There's Tenchi Muyo games on PCE, SF, and PS1, and four on Saturn, but I don't know if any are the same as Tenchi Muyo FX.
Welcome To Pia Carrot is also on PC, PC-98, and Saturn.
Zoku Hatukoi Monogatari is also on Saturn.