Yes that is perfect. All three identical speakers along the front is the very best solution but many times is not practical. If you want you can just set the extra speaker aside. Or you can even setup a 6.1 system using the extra C-100 as the sixth speaker in the middle rear. Normally the rear surrounds go on the side wall just behind the main listening area a foot or two and also up high, like 5-6 feet if possible. Sometimes placing the surrounds on the rear wall is the only practical option.

Be sure the center C-100 is in the vertical orientation and you do not place it over on its side (that is a no-no).

For best results keep the C-100's away from the wall at least a foot or two or three (again if practical).

Enjoy!