I have seen this happen with a few other plugins, often just from the plugin author changing the comments and not actual code. (Especially when a new WordPress version comes out, some authors will update the compatibility version of their plugin.)
I think it was on this support forum a long time ago that I heard it can be caused by the other plugin's author not releasing their new plugin version properly on wordpress.org, and just editing the existing plugin in place.
I can't find that original post, but another author of a different plugin explains that he did that with his plugin, at the end of this post from one of his users:
https://wordpress.org/support/topic/changes-in-files-detected-by-wordfence-plugin?replies=5
