Question about knitting two piece front for cardi

[Antares]

Hi!

I'm new here and new to knitting. I'm working on my first ever cardigan, and I have a few questions.

By the way, this is the Zip Front Cardigan (with flared sleeves) on Paton's site (only I adjusted the pattern so that mine doesn't have flared sleeves since I'm not a flared-sleeves type person). Happily THAT part of the project is going very well.

However, I have some questions about the two front pieces. The left front pattern says to work the ribbing and stockinette stitch for appropriate length and end with RS facing for next row.

Then, the right front pattern says to follow the same directions as for the left and for the same length but end with WS facing for next row.

So if I'm following the exact same pattern for both sides, won't I need to add an extra row to the right side to make it end with the WS? If I do that, won't that make the right side longer than the left side? How do I fix this?

Thanks in advance for any help you can provide.