for file in *
do
	sed -i 's/A1/Alice/g' "$file"
	sed -i 's/B1/Bob/g' "$file"
done

# Is equiv to:

for file in *;  do sed -i 's/A1/Alice/g' "$file"; sed -i 's/B1/Bob/g' "$file"; done

# Note the strange rule for 'do': it cannot have a semicolon directly after it,
# even though that would make sense :P  POSIX ftw