Packard bell with 2 harddrives

i have a packard bell force1999 with a pent133, i want to fdisk, reformat and upgrade to win98, when i opened the pc there are 2 harddrives inside, a sticker on the drives say they must be used as a set, in “my computer” only one harddrive shows up as c:, 2.1G,my question is…can i fdisk and format just like normal?
i have talked to a few other techs and they agree the 2 drives are working as one virtual drive..most have never seen or heard of this in a home pc, can anyone give me info? i would really like to hear from someone who has actually worked on or seen this before,thanks