Just two CDs. One with the Soviet campaign videos and the other with the Allied campaign videos. Other then that, both discs contained full copies of the game for both DOS and Windows 95 - users were encouraged to lend the other disc to a friend so you could play multiplayer.

This continued with Tiberian Sun and Red Alert 2. Generals came on two CDs but it used the “install disc” + “play disc” system rather than the “lend one to a friend” model used previously. Then CNC3 was released on a single DVD.

What a stunning era that was. I remember swapping discs with my friend after I finished one campaign.

I remember my friend borrowing the soviet disc and never giving it back... Til this day I've never played the soviet campaign.

I'm pretty sure it was only one CD. Keep in mind that the 600MB of CD was just huge at the time, so more than enough place for both versions.

At the time I had only an old 486 with a 500MB disk under DOS, and I played this game quite extensively.

I even remember cutting the sound to gain a few FPS, which enabled me to go from "unplayable" to "barely usable" ^^.

Red Alert was released on two CD's, Allied and Soviet, mostly because they each had the video clips for the campaign you were playing.

Same applies for Tiberian Sun. GDI and NOD CD's.

I have them all via the "The Command & Conquer Collection" released back in 2003.

Source:

Red Alert: https://i.imgur.com/xD7j08b.jpg

Tiberian Sun: https://i.imgur.com/xD7j08b.jpg

I have an edition of Red Alert somewhere that includes the expansions as well, which adds up to 4 CDs. It sounds big, but it's not unheard of in this era. Riven was released on 5 CDs and The 7th Guest on 7 CDs, if I remember correctly.