Fill Down Option Not To Interrupt Conditional Formatting

Below is a code that works for this attachment Invoice.xlsm When you hit the code you will see how the 2 left most columns disrupt the conditional formatting resulting in one color for those columns as opposed to every second row with one color and the rows between them another color. modify this code so that the conditional formatting remains the same? (I highlighted the part in the code that needs attention).

[Code] ......