Do speaker wires have to be the same length for each speaker?

No, but like most of us, if you had two different lengths, you’d always be wondering if it would sound better if they were. So mine are the same length even though I could have saved a few bucks if I hadn’t. But I like the reason above for keeping them the same length - resale value and ease to sell them.

After the Big Bang Symmetry was broken, accounting for the present scarcity of antimatter in our present Universe. There you go!

A storm is coming oldhvymec.

ok another question, can I splice 12 ga. to say 14 ga. wire? I don't have a high end system, just don't want to spend $$ on a roll of wire if I can avoid it. Old Pioneer sx980 w/ klipsh forte ii, standard A/T turntable + cambridge CD player.

Sure..., and all of the wires inside of every piece of equipment must be the same length for both channels.

And, all "mirror image" parts in both channels must sit equidistant from the power supply.