**If from the same source, you mean they are somehow bound together in either a creation-myth or are related in some particular fashion, yes, [The Pattern][1] and [the Logrus][2] (and their representative icons, the Unicorn and the Serpent) are related, though as readers the true relationship both of them is never revealed.** 

All we know is they are two of the Universe's primary forces, Order and Chaos, perhaps they are family or were "created" at the same time, or one is part of the other. What we do know, is they both seek ascendancy and control of the Universe and everything in it.

From Prince of Chaos:

>Both the Pattern and the Logrus are sentient," he said. "We've both seen evidence of that. Whether they are manifestations of the Unicorn and the Serpent or the other way around makes no real difference. Either way, we are talking about a pair of greater than human intelligences with vast powers at their disposal. Whichever came first is also one of those useless theological points." **-- Mandor, in Prince of Chaos.**

The Pattern, the Logrus and the [Jewel of Judgement][3] are manifestations of these cosmic entities who have been engaged in a battle since before recorded history. The Princes in [Amber][4] and in the [Courts of Chaos][5] are nothing but tools to alter the landscape of the universe for one side or the other.


  [1]: http://princeofamber.wikia.com/wiki/The_Pattern
  [2]: http://princeofamber.wikia.com/wiki/The_Logrus
  [3]: http://princeofamber.wikia.com/wiki/Jewel_of_Judgement
  [4]: http://princeofamber.wikia.com/wiki/Amber
  [5]: http://princeofamber.wikia.com/wiki/The_Courts_of_Chaos