Author name are created with extra word “by” in every new author name

Hey,
I am using your plugin and have a question. I have allowed the plugin to create new user when it import the post from the feed if the the author is not already user. Now the problem is every time the new user created by the plugin adds the additional word “By” in the start of user name.. You may have a look on the site https://www.clocksblog.com

or direct to a post https://www.clocksblog.com/with-classic-watch-tag-heuer-turns-back-time-at-baselworld-fair/ . Kindly let me know so I can fix this issue. If you say I can provide you login details.