i did not only give you the answer. mine is more than you asked for. you have full control of the color and transparency.

the color1 ....4 are all file textures. i only made some uniformly colored files, but they could be the pic of your grandma.

if you only want color one solid and color 2 50% transparent, you leave all as is, and delete the 2 connection of the "transparenc" named checker. and apply black to 1st color, and 50% grey to 2nd color.

but what you can do with my solution is replace one file texture with noise, and you have solid color 1 and noisy transparent color 2 in the checker ....

any more questions?