Frieeda Fan 

Oh dear as I would have expected that if you basically did 2 exports, they would be named differently.

After running through the process myself I see the only warning you get happens at the end of the process at which point the damage is done.

Great feedback, so please log this on the ideas page. 
In the meantime, does your MS Word have AutoSave enabled: 

Lyds

thanks for your kind reply, Lydia. I didn't receive the warning the way you received it, however, a window did pop up immediately after I clicked "Export for Bilingual Review," on which there was a pre-ticked option describing, as I recalled, that the previous bilingual review file would be overwritten. I skipped to the next step unfortunately, since I thought default setting was usually okay. And the file containing my changes was overwritten. Given this, the AutoSave of MS Word might be of no use.

thanks for your kind reply, Lydia. I didn't receive the warning the way you received it, however, a window did pop up immediately after I clicked "Export for Bilingual Review," on which there was a pre-ticked option describing, as I recalled, that the previous bilingual review file would be overwritten. I skipped to the next step unfortunately, since I thought default setting was usually okay. And the file containing my changes was overwritten. Given this, the AutoSave of MS Word might be of no use.