Luddite that I am, I merely backspace out the extra lines in the RTE, since it's generally an extra paragraph break that gets inserted by me that gets doubled.
I do exactly the same in the Word file. Since I use the "No Spacing" format, I don't get the automatic space between paragraphs when I type. I have to manually insert those breaks with the "enter" key when I type, so before I post, I just remove that paragraph break between the paragraphs, and the formatting retains the paragraph break at the end of the last line of the paragraph.
This is a legacy, mind you, from having begun to write on a manual typewriter with a black and red cloth ribbon. I treat paragraph breaks as carriage returns.