first was it a blue black or splash BLRW?
I'm willing to bet that it was a black BLRW and a golden laced wyandotte. If you think about it the color of both birds are black with just a touch of lacing color. When you cross colors even if the same breeds it's a mutt. You won't get the lacing. ( yes you can breed for years and years and perfect the lines and get a color out of it ) but for the purpose of this topic crossing colors of a breed is a mut.
Lacing is not a dominant gene. When it gets mixed into other colors it turns into blocky random colors.
I crossed a SLW over a Cornish X hen. The chicks came out white with black spots. I crossed a SLW over a bcm. Chicks came out all black. I crossed a SLW over a BLRW. Chicks came out black with white and red blotches.
Lacing is a fragile gene. Gotta keep it in the color to continue the lacing pattern.
Now you can cross a blue BLRW with a black BLRW to get a splash BLRW.
They are all BLRW just a different variation of it.
You can cross colors of a breed of they are solid colors. Like white,black or blue. The d tire bird is 1 color