I did some searching, and yeah, seems like that might work, though the BG1 soundsets have less files than BG2 ones, can't tell what the in game difference will be.
For more details, see
https://forums.beamdog.com/discussion/23894/character-voice-gone and
https://forums.beamdog.com/discussion/comment/399288#Comment_399288 .
What I'm doing, is giving the BG1 files new names (after copying them to temporary directory), and then will copy them to BG2 sounds directory for respective language (enUS in my case), then see if that works.
I also found a way to rename multiple files in Windows (to avoid renaming 300 something files manually), using Power Shell. If you are comfortable with command line consoles, see
http://www.howtogeek.com/111859/how-to-batch-rename-files-in-windows-4-ways-to-rename-multiple-files/ (there are also ways not involving Power Shell, with external software making it easier, but I didn't check them, since PS worked for me just fine).