Find the right size ohms power response etc - then replace in pairs.
You always replace stereo speaker system drivers in pairs, so they still sound the same. Your ears will tell the difference - you won't know why, but it "won't be right".
Odds are against coming up with an exact match, you just need to get Real Close.
Unless you track down the Asian OEM Supplier that made the raw speaker and they happen to have a box of them in the warehouse, and the odds on that are way long. Even at Logitech, their "warranty" is to toss the bad ones in the trash and give you a new set from current production.