Might have to watch doing the one color strings from multi's. The colors use different voltages and you could end up with a brighter string compared to the other. Can't remember the exact voltages but usually blue has higher voltage requirements when in series.
Yeah I've noticed that. Also, there are two types of bulbs in these strands. One bulb with a longer stem, and one with a shorter stubby stem. The longer one is the one used primarily throughout the strand, but right before the rectifier, they use the short one. You can swap out the LEDs inside of them, but the LED's themselves are very different. I have really only noticed a difference in brightness however, on the "converted" orange strands (which I don't intend on using anyways, except for Halloween)
But my Reds, Greens, and Blues are plenty bright
These sets come with two replacement bulbs, however they are always "long" blue and "long" red, no short ones