To make it as fair as possible, I'm not even using clones... it's just the same plant. My veg room has a 125W 2700K CFL hanging on one side and a 125W 6500K CFL on the other. One plant is positioned in the middle of the two lights, such that some of the plant receives a mixed spectrum, some receives mainly red light and some receives mainly blue light. Things I've noticed: Shoots receiving predominantly 2700K light have more spaced internodes, longer stalks and less useful growth. The stalks also appear very thin. Shoots receiving predominantly 6500K light have more compact internodes and the shortest overall stalk length. The stalks appear somewhat thin, but thicker than 2700K by a noticeable amount. Shoots receiving a mix of spectrums have the longest stalks, but the stalks are also much thicker and healthier looking, similar to how it'd look outdoors. And there is no fan even on this plant. They also seem to have the most compact internodes, but the spacing between internodes is weirdly long (thus the longest stalks). Overall, the plant looks much thicker on the blue side. The thickness and length of the stalks on those plants receiving a mix is surprising. Picture guide: 2700K side, 6500K side, 2700k internode spacing, 6500K internode spacing. For the internode spacing difference, look at the leaf sets closest to the main stalk. The 6500k ones are offset barely any, the 2700K ones are offset a lot and the mix are offset the least (though those aren't pictured. they're really not offset at all.)
Also worth noting is that the plant tends to lean towards the 2700K bulb, and the leaves between the bulbs prefer to face the 2700k.
If I flower it, I'll likely just do it outside next year. For the time being it's a mom. Durban Poison. My flowering room isn't really designed for tall plants. I'll be posting another grow log sometime soon. My indoor grow this summer has been rather troubled. Every bug under the book and a bag of medium that was a different composition than it was supposed to be because I bought an old bag.