AND!!!
i see this
#define totalleds 15
Adafruit_TLC5947 tlc = Adafruit_TLC5947(totalleds, clock, data, latch);
Must be
#define NUM_TLC5974 2
Adafruit_TLC5947 tlc = Adafruit_TLC5947(NUM_TLC5974, clock, data, latch);
your saying to the library you used 15 driver so 360! Channels or 120 RGB leds.
so when you use tlc.write it send all Data for 15 drivers!
as the sketch says
// How many boards do you have chained?
#define NUM_TLC5974 1