Easiest way to be sure is to use a voltmeter. I would guess that the black is ground on both (most negative cell), the middle red is the same as the blue (middle cell), and the last reds are the same on both (most positive cell).
You should know by now to use protection. At least here. Latex gloves at the very least, or maybe even something less revealing (can still make out the shape) depending on your inhibition level...