Adafruit_NeoPixel define pin for different setups
The “hint of blue on the strip” is a consequence of your second loop in rgbFadeInAndOutStrip1() ending with the test b &gt; 0.  Because of that, the last strip1.setPixelColor() call sets the color to (0,0,1), a faint blue, instead of (0,0,0), off.  Here is some revised code that works ok:

#include &lt;Adafruit_NeoPixel.h&gt;
#include &lt;avr/power.h&gt;
enum { rgbPin1=8, rgbPin2=7, LEDcount=11, ledFadeTime=5};

Adafruit_NeoPixel strip1 = Adafruit_NeoPixel(LEDcount, rgbPin1);
Adafruit_NeoPixel strip2 = Adafruit_NeoPixel(LEDcount, rgbPin2);

void setup() {
  strip1.begin();
  strip1.show(); // Initialize all pixels to 'off'
  strip2.begin();
  strip2.show(); // Initialize all pixels to 'off'
}

void loop() {
  rgbFadeInAndOutStrip1(0, 0, 255, ledFadeTime); // Blue
  rgbFadeInAndOutStrip2(255, 0, 0, ledFadeTime); // red
}

void fadeStrip(Adafruit_NeoPixel *strip, int bval, int bdir, uint8_t red, uint8_t green, uint8_t blue, uint8_t wait) {
  for(uint8_t b=0; b&lt;255; ++b) {
    bval += bdir;
    for(uint8_t i=0; i&lt;strip-&gt;numPixels(); ++i) {
      strip-&gt;setPixelColor(i, red * bval/255, green * bval/255, blue * bval/255);
    }
    strip-&gt;show();
    delay(wait);
  } 
}

void rgbFadeInAndOutStrip1(uint8_t red, uint8_t green, uint8_t blue, uint8_t wait) {
  fadeStrip(&amp;strip1, -1, 1,   red, green, blue, wait);
  fadeStrip(&amp;strip1, 255, -1, red, green, blue, wait);
}

void rgbFadeInAndOutStrip2(uint8_t red, uint8_t green, uint8_t blue, uint8_t wait) {
  fadeStrip(&amp;strip2, -1, 1,   red, green, blue, wait);
  fadeStrip(&amp;strip2, 255, -1, red, green, blue, wait);
}


Note, since I ran tests on an Uno rather than a Leonardo, I attached pixel strings to pins 7 and 8 rather than 17 and 18.  I used enum to define constants, rather than declaring constants as variables, and factored some common code into functions rather than reduplicating it.

Following is another program (which I call neocycle6) you can use to test two strips.  Note, it only counts colors down to 1 rather than 0 because I like the effect of leftover pixels glowing faintly.  Also note: the round boards I used have only 7 LEDs each, so I set PixelCount to 7, not 11; this uses pins 7 and 8, not 17 and 18; I don't drive the brightness beyond 77 since the LEDs are so bright anyway; and it doesn't have an
#include &lt;avr/power.h&gt; statement, which you can add if needed.

// Drive 2 sets of 7 ea. WS2812 NeoPixels through sets of colors.
// jw 11 September 2015  
#include &lt;Adafruit_NeoPixel.h&gt;

// Select pin# connected to NeoPixels strand, and number of NeoPixels.
enum { PixelPinA=7, PixelPinB=8, PixelCount=7 };
// Create a NeoPixels device structure
Adafruit_NeoPixel pixelA = Adafruit_NeoPixel(PixelCount, PixelPinA);
Adafruit_NeoPixel pixelB = Adafruit_NeoPixel(PixelCount, PixelPinB);

void setup() {
  byte i, j=0;
  pixelA.begin();               // Init. NeoPixel data structure
  pixelB.begin();               // Init. NeoPixel data structure
}

uint8_t c=1, d=1, p=0, v=1;
void loop() {
  c += d;
  if (c&gt;76)
    d = -1;                     // Go down when done going up
  else {
    if (c&lt;2) {                  // Set up for next pixel
      d = 1; p = (p+1)%PixelCount;
      if (!p) ++v;              // Rotate the weights to next color
    }
  }

  pixelA.setPixelColor(p, c*(v&amp;1), c*((v&amp;2)/2), c*((v&amp;4)/4));
  pixelB.setPixelColor(p, c*((v&amp;2)/2), c*(v&amp;1), c*((v&amp;4)/4));
  pixelA.show();               // Show updated colors
  pixelB.show();               // Show updated colors
  delay(9 + 300/c);            // Ramp small numbers more slowly
}