Virtually ALL speaker wire is marked, some are just marked very subtly. One of the wire will have a stripe, or one or more molded ridges, or it will have writing that can be printed or embossed into the insulation. You can choose to have that marked wire Positive (red) or Negative (black) as long as once you make that decision, you are always consistent with it. I choose to have the marked wire be Positive (red).
I think if you look closely, you will see something on one wire that is not on the other so you can tell the wires apart. I think I can guarantee that with 99.9% certainty.
As has been said, as long as the Red on the Amp, connects to the Red on the Speakers, and black to black, you will be fine.
Steve/bluewizard