While I wouldn't bet money I could hear a difference, I agree their could be some resistance issues , and factor in if you try an upgrade your speaker cables in the future, you will have a "tough sell" on your old un equal length pair of speaker cables.
Does unequal speaker wire length matter?
My amp is not located centrally between my speakers. Due to the layout of my listening area, the amp is about 10 feet from one speaker, and adjacent to the other - and this will not change. I am currently using two 4-meter cables, but one of them need only be about 1 meter. I am looking to upgrade my cables, could I get away with unequal lengths and save a good bit of money?