Question
I separated a pot that had two phal orchids growing together, I used a knife to separate the area that was fused.  After a few weeks the leaves are becoming very dark green and some reddish coloring as well. The are in the same location in which they thrived for years and flowered. I have fertilized them and they are close to the window.

Answer
Jody, if your question is to know why the leaves are dark green with some reddish.  Nothing you have said suggests to me any problem with these plants. Redish coloration usually indicates high light exposure while dark green indicates low light exposure.  If the plants are otherwise healthy, the reddish coloration may be due to an area on the plant that gets some exposure (even if temporary) to bright sunlight or focused sunlight.  Sometimes the sun rays can be focused like a lens on one particular area of a leaf or leaves causing that area to be more of a reddish color. As long as the leaf is not actually turning black from sunburn it should be fine, but keep a watchful eye.