Let's say you get a 20 foot cable and then a 10 foot cable. Electrical signals in a copper wire travel at approximately 2/3 the speed of light so the sound could be just under 10 nanoSeconds off compared to the other cable.
I've seen audiophiles that claim they can hear that difference.
PS. In short, no, no and no.
I have a pair of 12 AWG speaker cables. I am looking at getting 3 additional pairs to complete a surround sound system. I read somewhere that the cables should all be the same length but should they all be from the same manufacturer (I will keep the gauge the same).