Why the Spooky2 Remote LED lights are equally bright, blink slowly or both off sometimes?

The Spooky Remote LEDs' state is governed by two things - the wave's shape, and the speed of the frequency. What you're seeing is how the frequencies control the LEDs.

The first thing to understand is that the twin LEDs are never actually both lit at the same time, despite what your eyes tell you. Every waveform has a positive and a negative phase, and each phase lights one LED. Since a wave can never be positive and negative at the same time, the LEDs can never both be lit at the same time.

Frequency is measured in Hertz (Hz), which used to be called "Cycles Per Second" (CPS). A 1Hz frequency will cycle the waveform from positive to negative and back once every second.

With a low slow frequency like 0.5Hz, the wave's polarity flips from positive to negative once every two seconds, so the LEDs will light alternately and slowly. With a frequency of 60,000Hz, the polarity flip happens 60,000 times every second, far too fast for your eyes to register. So both LEDs now appear to be equally bright.

With a very high frequency like 7MHz, the state is flipping seven million times a second. And this is simply too fast to allow either LED to even respond to the "LED on" command before the next "LED off" command is received. So the LEDs appear to be unlit.

But they'll return to normal with the next mid-range frequency.

Please check the blog and understand:
How Does Spooky Remote Light
http://www.spooky2-mall.com/blog/how-does-spooky-remote-light/