No, I wouldn't go with matching pillows, but I would go with ones that are similar so they look like they belong together. For example, if find something you like in a flower print, try to find another flower print with similar colors, but not an identical pillow.

There is no definitive formula, but if you use at least one of the pillows on both sofas - not necessarily in the same numbers - you will be fine. Otherwise, just make sure all the colors and patterns coordinate. Places like West Elm make this easy for you.