Label the columns with three labels — 0 if the two cells are the same, 1 if red is on top, 2 if blue is on top. Then break it into contiguous chunks with the same label.

Chunks with label 0 can be ignored because we can cover them completely with vertical pairs. The other chunks can be covered with horizontal pairs if the length of the chunk is even. Otherwise, we have one column left over which we can flip a cell of so we can cover it with a vertical pair. So the answer is the count of all chunks with odd length that are labeled 1 or 2.

Solution

o7 saluting a fellow new CM, onwards to that shiny yellow (orange? gold?) name!