If the color in column A is being changed by conditional formatting, set up
the same condition in the column B cell, but referencing column A (use
Formula Is instead of Cell Value Is).
For example, lets say you set up a conditional format for Cell A2 that says
if its value is 5, set the background as Red. Then in B2 we'd set up
conditional format as
Formula Is and enter =$A$2=5 and set the background color to Red also.
It is in the drop down list when you first start Conditional Formatting. It
is initially displayed as [Cell Value Is] followed by something like
"between" and a couple of data entry boxes.
Just click the arrow on the [Cell Value Is] and you'll see [Formula Is] and
the rest of the form will change based on that.